How would you rewrite the expression 30a^3 + 40a^5 by factoring out the GCF?

10a^3(3 + 4a^2)
10a^2(3 + 4a^2)
5a^3(6 + 8a^2)
10a^3 (3a + 4a^2)

10a^3(3 + 4a^2)