Convert.ToString() vs ToString() vs new string()

Question

I am doing string reverse while I have some problem with that. I have added code and O/P below. Please give me the detail explanation for this solution. I am beginner in C#. 

 

CODE

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = "ganesh";
            Console.WriteLine(new string(str.Reverse().ToArray()));
            Console.WriteLine(Convert.ToString(str.Reverse().ToArray()));
            Console.WriteLine((str.Reverse().ToArray()).ToString());
            Console.ReadKey();
        }
    }
}

  OUTPUT

hsenag
System.Char[]
System.Char[]