$$\text { Find the derivative of } y \text { with respect to } x , t , \text { or } \theta \text {, as appropriate. }$$

Multiple Choice

$$\text { Find the derivative of } y \text { with respect to } x , t , \text { or } \theta \text {, as appropriate. }$$
- $$y = 9 x e ^ { x } - 9 e ^ { x }$$

A) $9 e ^ { x }$
B) $9 x e ^ { x } + 18 e ^ { x }$
C) $9 x e ^ { x }$
D) $9 \mathrm { x }$