Arrays - General Questions

Arrays in C# are derived from:

What is the output of the following program?

int[] a = { 2, 4, 6, 8 };
Console.WriteLine(Array.IndexOf(a, 6));

What is the output of the following program?

int[,] m = new int[2, 3];
Console.WriteLine(m.GetLength(1));

What is the output of the following program?

int[][] j = { new[] { 1 }, new[] { 2, 3, 4 } };
Console.WriteLine(j[1].Length);

What is the output of the following program?

int[] a = new int[3];
Console.WriteLine(a[1] + " " + a.Length);