using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        List<string> list1 = new List<string>{"A", "B", "C"};

        List<string> list2 = new List<string>{"=", "<", ">"};

        List<string> list3 = new List<string>{"1", "2", "3"};

        string result = string.Join(" AND ", list1.Zip(list2, (l1, l2) => l1 + l2).Zip(list3, (l2, l3) => l2 + l3));

        Console.WriteLine(result);

    }

}