a)int a( 10)； //The definition format of array is: data type array name [constant expression]; You can only use [] but not (), so it is wrong.

B) int n= 10，a[n]； //Definition: Constant expressions in array name [Constant Expression] can only be integer constants and symbolic constants, and can never be variables, so both B and C are wrong.

c)int n； scanf("%d "，& ampn)int a[n]；

d)# define SIZE 10 int a[SIZE]； //Correct