$\text { Determine the open intervals on which the graph of } y = - 6 x ^ { 3 } + 8 x ^ { 2 } + 6 x - 5 \text { is }$

Multiple Choice

$\text { Determine the open intervals on which the graph of } y = - 6 x ^ { 3 } + 8 x ^ { 2 } + 6 x - 5 \text { is }$ concave downward or concave upward.

A) concave downward on $( - \infty , \infty )$
B) concave upward on $\left( - \infty , - \frac { 4 } { 9 } \right) ;$ concave downward on $\left( - \frac { 4 } { 9 } , \infty \right)$
C) concave upward on $\left( - \infty , \frac { 4 } { 9 } \right) ;$ concave downward on $\left( \frac { 4 } { 9 } , \infty \right)$
D) concave downward on $\left( - \infty , - \frac { 4 } { 9 } \right) ;$ concave upward on $\left( - \frac { 4 } { 9 } , \infty \right)$
E) concave downward on $\left( - \infty , \frac { 4 } { 9 } \right) ;$ concave upward on $\left( \frac { 4 } { 9 } , \infty \right)$