Answer:The third optionStep-by-step explanation:Given(a + 3)(- 2a² + 15a + 6b²)Each term in the second factor is multiplied by each term in the first factor, that isa(- 2a² + 15a + 6b²) + 3(- 2a² + 15a + 6b²) ← distribute both parenthesis= - 2a³ + 15a² + 6ab² - 6a² + 45a + 18b² ← collect like terms= - 2a³ + 9a² + 45a + 6ab² + 18b² → C