using System;

using System.Collections.Generic;

​

public class Program

{

    public static IEnumerable<int> GetRow(int[, ] array, int index)

    {

        for (var i = 0; i <= array.GetUpperBound(0); i++)

            yield return array[i, index];

    }

​

    static void Main(string[] args)

    {

        var test = new[, ]{{1, 2}, {3, 4}, {5, 6}, {7, 8}};

        for (var j = 0; j <= test.GetUpperBound(1); j++)

            Console.WriteLine("[" + string.Join(", ", GetRow(test, j)) + "]");

    }

}