Simplify the Expression $$\left( x ^ { 9 } \right) ^ { 4 }$$

Multiple Choice

Simplify the expression. Write your answer with positive exponents only.
- $$\left( x ^ { 9 } \right) ^ { 4 }$$

A) $x ^ { 6,561 }$
B) $x ^ { 13 }$
C) $x ^ { 36 }$
D) $x ^ { 5 }$