Simplify the Expression $\left(\frac{x}{3 y}\right)^{-4}$ A) $\frac{x^{4}}{81 y^{4}}$ B) $\frac{3 y^{4}}{x^{4}}$ C) $-\frac{x^{4}}{81 y^{4}}$

Multiple Choice

Simplify the expression. Write the result without using negative exponents. (Assume all variables represent nonzero real numbers.)
- $\left(\frac{x}{3 y}\right) ^{-4}$

A) $\frac{x^{4}}{81 y^{4}}$

B) $\frac{3 y^{4}}{x^{4}}$

C) $-\frac{x^{4}}{81 y^{4}}$

D) $\frac{81 y^{4}}{x^{4}}$