The functions $f$ and $g$ are given by $f ( x ) = 3 x ^ { 2 } + 12 x + 4$ and $g ( x ) = x ^ { 3 } + 6 x ^ { 2 } + 9 x - 8$.
What is the complete set of values of $x$ for which one of the functions is increasing and the other decreasing?
A $x \geq - 1$
B $x \leq - 1$
C $\quad - 3 \leq x \leq - 2 , x \geq - 1$
D $x \leq - 2 , x \geq - 1$
E $\quad x \leq - 3 , - 2 \leq x \leq - 1$
F $x \leq - 3 , x \geq - 2$
G $\quad - 2 \leq x \leq - 1$