GWD 22-21

Q21:

If x and y are positive integers, what is the value of (x+y)²?

(1)   x = y - 3

(2) x and y are prime numbers.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

答案选C，请问如何解答？

拜谢~