Which is easier to understand/maintain? A or B?

FindSampleSpecs_A.cs

using System;
using System.Collections.Generic;
using System.Linq;

using DuplicateFinder.Core.Commands;

using Machine.Specifications;

namespace DuplicateFinder.Core.Integration.Tests {

	public class When_duplicates_are_searched_by_size {
		static ICommand Command;

		Establish context =
			() => { Command = new CommandLineParser().Parse(@"--size --whatif Samples\First Samples\Second".Args()); };

		Because of = () => Command.Execute();

		It should_find_files_of_the_same_size =
			() => Command.AllDuplicates().ShouldContainOnly(@"Samples\First\content-full-first.txt",
															@"Samples\Second\content-full-second.txt",
															@"Samples\First\size-first.txt",
															@"Samples\Second\size-second.txt");
	}

	public class When_duplicates_are_searched_by_name {
		static ICommand Command;

		Establish context =
			() => { Command = new CommandLineParser().Parse(@"--name --whatif Samples\First Samples\Second".Args()); };

		Because of = () => Command.Execute();

		It should_find_files_with_the_same_name =
			() => Command.AllDuplicates().ShouldContainOnly(@"Samples\First\name.txt",
															@"Samples\Second\name.txt");
	}

	public class When_duplicates_are_searched_by_contents {
		static ICommand Command;

		Establish context =
			() => { Command = new CommandLineParser().Parse(@"--content --whatif Samples\First Samples\Second".Args()); };

		Because of = () => Command.Execute();

		It should_find_files_with_the_same_contents =
			() => Command.AllDuplicates().ShouldContainOnly(@"Samples\First\content-full-first.txt",
															@"Samples\Second\content-full-second.txt");
	}

	public class When_duplicates_are_searched_by_head_contents {
		static ICommand Command;

		Establish context =
			() => { Command = new CommandLineParser().Parse(@"--content --first 5 --whatif Samples\First Samples\Second".Args()); };

		Because of = () => Command.Execute();

		It should_find_files_with_the_same_contents_in_the_first_five_bytes= 
			() => Command.AllDuplicates().ShouldContainOnly(@"Samples\First\content-full-first.txt",
															@"Samples\Second\content-full-second.txt",
															@"Samples\First\content-head-first.txt",
															@"Samples\Second\content-head-second.txt");
	}

	public class When_duplicates_are_searched_by_tail_contents {
		static ICommand Command;

		Establish context =
			() => { Command = new CommandLineParser().Parse(@"--content --last 5 --whatif Samples\First Samples\Second".Args()); };

		Because of = () => Command.Execute();

		It should_find_files_with_the_same_contents_in_the_first_five_bytes =
			() => Command.AllDuplicates().ShouldContainOnly(@"Samples\First\content-full-first.txt",
															@"Samples\Second\content-full-second.txt",
															@"Samples\First\content-tail-first.txt",
															@"Samples\Second\content-tail-second.txt");
	}

	public class When_duplicates_are_searched_by_head_and_tail_contents {
		static ICommand Command;

		Establish context =
			() => { Command = new CommandLineParser().Parse(@"--content --first 5 --last 5 --whatif Samples\First Samples\Second".Args()); };

		Because of = () => Command.Execute();

		It should_find_files_with_the_same_contents_in_the_first_and_last_five_bytes =
			() => Command.AllDuplicates().ShouldContainOnly(@"Samples\First\content-full-first.txt",
															@"Samples\Second\content-full-second.txt");
	}

	// Extension Methods
	internal static class Extensions {
		public static string[] Args(this string args) {
			return args.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
		}
		static T As<T>(this object instance) {
			return (T) instance;
		}
		public static IEnumerable<string> AllDuplicates(this object instance) {
			return instance.As<FindDuplicatesCommand>().Duplicates.SelectMany(x => x);
		}
	}
}

FindSampleSpecs_B.cs

using System;
using System.Collections.Generic;
using System.Linq;

using DuplicateFinder.Core.Commands;

using Machine.Specifications;

namespace DuplicateFinder.Core.Integration.Tests {

	public class FindingDuplicates {

	    It can_find_files_with_the_same_size =()=> {
		RunCommand(@"--size --whatif Samples\First Samples\Second");
		AllDuplicates.ShouldContainOnly(@"Samples\First\content-full-first.txt",
						@"Samples\Second\content-full-second.txt",
						@"Samples\First\size-first.txt",
						@"Samples\Second\size-second.txt");
	    };

	    It can_find_files_with_the_same_name =()=> {
		RunCommand(@"--name --whatif Samples\First Samples\Second");
		AllDuplicates.ShouldContainOnly(@"Samples\First\name.txt", @"Samples\Second\name.txt");
	    };

	    It can_find_files_with_the_same_contents =()=> {
		RunCommand(@"--content --whatif Samples\First Samples\Second");
		AllDuplicates.ShouldContainOnly(@"Samples\First\content-full-first.txt", @"Samples\Second\content-full-second.txt");
	    };

	    It can_find_files_with_the_same_head_content =()=> {
		RunCommand(@"--content --first 5 --whatif Samples\First Samples\Second");
		AllDuplicates.ShouldContainOnly(@"Samples\First\content-full-first.txt",
						@"Samples\Second\content-full-second.txt",
						@"Samples\First\content-head-first.txt",
						@"Samples\Second\content-head-second.txt");
	    };

	    It can_find_files_with_the_same_tail_content =()=> {
		RunCommand(@"--content --last 5 --whatif Samples\First Samples\Second");
		AllDuplicates.ShouldContainOnly(@"Samples\First\content-full-first.txt",
						@"Samples\Second\content-full-second.txt",
						@"Samples\First\content-tail-first.txt",
						@"Samples\Second\content-tail-second.txt");
	    };

	    It can_find_files_with_the_same_head_and_tail_content =()=> {
		RunCommand(@"--content --first 5 --last 5 --whatif Samples\First Samples\Second");
		AllDuplicates.ShouldContainOnly(@"Samples\First\content-full-first.txt", @"Samples\Second\content-full-second.txt");
	    }
	    
	    // Helpers
	    static ICommand Command;
	    static ICommand RunCommand(string command) {
		var args = command.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
		Command  = new CommandLineParser().Parse(args);
		Command.Execute();
		return Command;
	    }
	    static IEnumerable<string> AllDuplicates {
		get { return (Command as FindDuplicatesCommand).Duplicates.SelectMany(x => x); }
	    }
	}
}