Second Derivative and Points of Inflection

The second derivatives of the twice-differentiable functions $f$, $g$, and $h$ are given by:

$\displaystyle f''(x) = x(x - 1)^2 (x + 2)^3$

$\displaystyle g''(x) = x(x - 1)^2 (x + 2)^3 + 1$

$\displaystyle h''(x) = x(x - 1)^2 (x + 2)^3 - 1$

Which of the functions $f$, $g$, and $h$ have a graph with exactly two points of inflection?