If m(x) = x2 + 3 and n(x) = 5x + 9, which expression is equivalent to (mn)(x)?

The notation (mn)(x) means multiply the functions: m(x)n(x) = (x² + 3)(5x + 9). Distribute each term: 5x³ + 9x² + 15x + 27. This matches choice A.

AI-written and checked against the verified answer.