Which of the following quartic functions has x = -2 and ax = -3 as its only two real zeros?
1) f(x) = x⁴ + 5x³ + 6x² + 4x + 1
2) f(x) = x⁴ + 3x³ + 2x² + 4x + 3
3) f(x) = x⁴ + 2x³ + 3x² + 4x + 5
4) f(x) = x⁴ + 4x³ + 6x² + 5x + 1