Use the Laws of Exponents to Simplify Each Expression Using $$\left( - 3 x ^ { 4 } \right) \left( 6 x ^ { 5 } \right)$$

Multiple Choice

Use the laws of exponents to simplify each expression using positive exponents only. Assume all variables represent nonzero real numbers.
- $$\left( - 3 x ^ { 4 } \right) \left( 6 x ^ { 5 } \right)$$

A) $- 18 x ^ { 20 }$
B) $18 x ^ { 20 }$
C) $- 18 x ^ { 9 }$
D) $18 x ^ { 9 }$