Replace explicit interface implementation.

Program.cs

//https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/language-specification/interfaces#interface-implementation-inheritance
class Program
{
    static void Main(string[] args)
    {
        IFoo @base = new Base();
        IFoo derived = new Derived();


        Console.WriteLine(@base.Bar()); //=> Base
        Console.WriteLine(derived.Bar()); //=> Derived
        Console.ReadLine();
    }
}

public interface IFoo
{
    string Bar();
}

public class Base : IFoo
{
    string IFoo.Bar() => "Base";
}

public class Derived : Base, IFoo
{
    string IFoo.Bar() => "Derived";
}