Answer:
-2a²+9a²+45a+6ab²+18b²
Explanation:
The distributive property is useful for sorting this out.
(a +3)(-2a² +15a +6b²)
= a(-2a² +15a +6b²) +3(-2a² +15a +6b²)
= -2a³ +15a² +6ab² -6a² +45a +18b²
Only the a² terms can be combined, so the product is ...
= -2a³ +9a² +45a +6ab² +18b² . . . . . matches the 3rd choice here