Simplify Express Your Answer with Positive Exponents $$\left( - 4 x ^ { - 3 } \right) \left( 9 x ^ { - 5 } \right)$$

Multiple Choice

Simplify. Express your answer with positive exponents. Assume that all variables are nonzero.
- $$\left( - 4 x ^ { - 3 } \right) \left( 9 x ^ { - 5 } \right)$$

A) $x ^ { 15 }$
B) $- 36 x ^ { 8 }$
C) $- 36 x ^{15}$
D) $\frac { - 36 } { x ^ { 8 } }$