using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var type1 = "a,b,c";

        var type2 = new string[3] { "a", "b", "c" };

        var result1 = string.Join(',', type1.Split(',').Select(x => $"'{x}'"));

        var result2 = string.Join(',', type2.Select(x => $"'{x}'"));

        Console.WriteLine($"Type1 : {result1}");

        Console.WriteLine($"Type2 : {result2}");

    }

}