Array operations with n-dimensional array using LINQ (C#)

Question

Assume we have a jagged array

int[][] a = { new[] { 1, 2, 3, 4 }, new[] { 5, 6, 7, 8 }, new[] { 9, 10, 11, 12 } };

To get a sum of second row a

Answer 1

A simpler way is doing like below

 var t = new List>();
 int[][] a = t.Select(x => new int[]{ x.Item1, x.Item2}).ToArray();