Strong password generator with C#

PasswordGenerator.cs

public static class PasswordGenerator
    {

        [Flags]
        public enum PasswordGenerationOptions
        {
            HasDigit       = 0b0001,
            HasLowerLetter = 0b0010,
            HasUpperLetter = 0b0100,
            HasSpecialChar = 0b1000,
            All            = 0b1111
        }


        public static PasswordGenerationOptions LettersAndDigits = PasswordGenerationOptions.HasDigit | PasswordGenerationOptions.HasLowerLetter | PasswordGenerationOptions.HasUpperLetter;
        public static PasswordGenerationOptions LettersAndSpecialChars = PasswordGenerationOptions.HasSpecialChar | PasswordGenerationOptions.HasLowerLetter | PasswordGenerationOptions.HasUpperLetter;


        private static Dictionary<PasswordGenerationOptions, string> _randomChars = new Dictionary<PasswordGenerationOptions, string>()
        {
            {PasswordGenerationOptions.HasDigit,"123456789"},
            {PasswordGenerationOptions.HasUpperLetter,"ABCDEFGHJKLMNPQRSTUVWXYZ"},
            {PasswordGenerationOptions.HasLowerLetter,"abcdefghjkmnpqrstuvwxyz"},
            {PasswordGenerationOptions.HasSpecialChar,"!@$?"},
        };



        public static string Generate(int requiredLength = 6, PasswordGenerationOptions options = PasswordGenerationOptions.All)
        {
            if (requiredLength < 6)
                requiredLength = 6;

            Random rand = new Random(Environment.TickCount);
            var result = String.Empty;

            var optionValues = Enum.GetValues(typeof(PasswordGenerationOptions)).Cast<PasswordGenerationOptions>();
            var hasSpecialChar = (options & PasswordGenerationOptions.HasSpecialChar) == PasswordGenerationOptions.HasSpecialChar;

            // Count provided options discarding PasswordGenerationOptions.All		
            var optionCount = optionValues.Aggregate(0, (acc, opt) => (options & opt) == opt && opt != PasswordGenerationOptions.All ? acc + 1 : acc);

            // Pick all provided options except PasswordGenerationOptions.All 
            var effectiveOptions = optionValues.Where(opt => (options & opt) == opt && opt != PasswordGenerationOptions.All).ToList();

            var specialCharCnt = requiredLength % 2 == 0 ? 2 : 1;
            optionCount = hasSpecialChar ? optionCount - 1 : optionCount;
            var len = hasSpecialChar ? requiredLength - specialCharCnt : requiredLength;
            var minSliceLen = Math.DivRem(len, optionCount, out int rem);

            var randomizedOptions = effectiveOptions.Select(opt => new { idx = rand.Next(0, effectiveOptions.Count - 1), option = opt }).OrderBy(r => r.idx).Select(r => r.option).ToList();

            foreach (var option in randomizedOptions)
            {
                var isOptionHasSpecialChar = option == PasswordGenerationOptions.HasSpecialChar;

                // PasswordGenerationOptions.HasSpecialChar has fixed slice length of 2
                var sliceLen = isOptionHasSpecialChar ? specialCharCnt : minSliceLen;

                result += PickChars(option, sliceLen);

                // Pick the extra resulting from the remainder
                if (!isOptionHasSpecialChar && rem > 0)
                {
                    result += PickChars(option, 1);
                    rem--;
                }
            }
            return Randomize(result);
        }

        private static string PickChars(PasswordGenerationOptions option, int count)
        {
            var result = String.Empty;
            Random rand = new Random(Environment.TickCount);
            var allChars = _randomChars[option];
            for (var i = 0; i < count; i++)
            {
                result += allChars[rand.Next(0, allChars.Length - 1)];
            }
            return result;
        }

        private static string Randomize(string value)
        {
            Random r = new Random();
            var len = value.Length;
            return new string(value.ToCharArray().OrderBy(s => r.Next(0, len - 1)).ToArray());
        }
    }