Answer:
(9a^3 + 10)(9a^3 - 10)
Step-by-step explanation:
81a^6 - 100
= (9a^3)^2 - 10^2 ---->(Difference of 2 squares)
= (9a^3 + 10)(9a^3 - 10)
It's C. (9a^3-10)(9a^3+10
