If a is an array of 5 integers then which of the following is the correct way to increase its size to 10 elements?

• int[] a = new int[5]; int[] a = new int[10];
• int[] a = int[5]; int[] a = int[10];
• int[] a = new int[5]; a.Length = 10 ;
• int[] a = new int[5]; a = new int[10];
• int[] a = new int[5]; a.GetUpperBound(10);