5 x 3n

15, 30, 45, 60

5, 15, 45, 135

0, 15, 45, 135

15, 45, 135, 405

The expression 5 x 3n means multiply 5 by 3 and then multiply that product by n. Therefore, the answer depends on the value of n. Without knowing the value of n, we cannot determine which of the options is correct.