Simplify the Expression $\left( 2 a ^ { 7 } \right) \cdot \left( 5 a ^ { 2 } \right)$

Multiple Choice

Simplify the expression. Assume all variables represent nonzero real numbers.
- $\left( 2 a ^ { 7 } \right) \cdot \left( 5 a ^ { 2 } \right)$

A) $7 ^ { 9 }$
B) $10 a ^{14}$
C) $10 a ^ { 9 }$
D) $7 ^ { 14 }$