Simplify the Expression $\left( 3 a ^ { 3 } \right) \cdot \left( 5 a ^ { 8 } \right)$

Multiple Choice

Simplify the expression. Assume all variables represent nonzero real numbers.
- $\left( 3 a ^ { 3 } \right) \cdot \left( 5 a ^ { 8 } \right)$

A) $15 a ^{11}$
B) $8 ^ { 24 }$
C) 15 a²⁴
D) 8¹¹