Solve the Equation by Expressing Each Side as a Power $729 ^ { x } = 81$

Multiple Choice

Solve the equation by expressing each side as a power of the same base and then equating exponents.
- $729 ^ { x } = 81$

A) $\left\{ \frac { 2 } { 3 } \right\}$
B) $\left\{ \frac { 3 } { 2 } \right\}$
C) $\left\{ \frac { 4 } { 5 } \right\}$
D) $\{ 4 \}$