Which polynomial represents the sum below?

(2x6 + 3x2 + 9) + (3x2 + x + 8)

A. 5x8 + 3x4 + x + 17
B. 5x8 + 3x2 + x + 17
C. 2x6 + 6x3 + 17
D. 2x6 + 6x2 + x + 17