find the difference. (9a^4+2a^2+5)-(16a^4-7a^2+1)
A25a^4-5a^2-4
B-7a-5a^2+6
C25a^8+9a^4+6
D-7a^4+9a^2+4
A25a^4-5a^2-4
B-7a-5a^2+6
C25a^8+9a^4+6
D-7a^4+9a^2+4