Which of the following best describes $$a_n + b_n$$ for even n?

A

$$q(pq)^{(n/2) -1}(p+q)^{n/2}$$

B

$$q(pq)^{(n/2) -1}(p+q)$$

C

$$qp^{n/2} (p+q)$$

D

$$q^{n/2}(p+q)$$

E

$$q^{n/2}(p+q)^{n/2}$$