(8x^5 + 9)(8x^3 + 9)
FOIL...first outside inside last
F....multiply first terms in each set.....8x^5 * 8x^3 = 64x^8
O...multiply outside terms in each set....8x^5 * 9 = 72x^5
I....multiply inside terms in each set....9 * 8x^3 = 72x^3
L...multiply last terms in each set.....9 * 9 = 81
now we have : 64x^8 + 72x^5 + 72x^3 + 81...and this cant be simplified...so ur answer is C
