Answer already submitted 
but the below code may be help
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplication1
{
class Program
{
    public static int i = 0;
    public static string[] S = new string[] { "A", "B", "C", "D", "E", "F" };
    static void Main(string[] args)
    {
        Console.Write("Please Select : "+S[i]);
        ConsoleKeyInfo K = Console.ReadKey(); 
        while (K.Key.ToString() != "Enter")
        {
            Console.Write(ShowOptions(K));
            K = Console.ReadKey();
        }
        Console.WriteLine("");
        Console.WriteLine("Option Selected : " + S[i]);
        Console.ReadKey();
        }
    public static string ShowOptions(ConsoleKeyInfo Key)
    {
        if(Key.Key.ToString() == "UpArrow")
        {
            if (i != S.Length-1)
                return "\b\b" + S[++i];
            else 
                return "\b\b" + S[i];
        }
        else if (Key.Key.ToString() == "DownArrow")
        {
            if(i!=0)
            return "\b\b" + S[--i];
            else 
                return "\b\b" + S[i];
        }
        return "";
    }
}
}