To use the Power Rule of Exponents, we apply the rule that states \( (a^m)^n = a^{m \cdot n} \).
In the case of \( (6^6)^3 \):
- We have \( 6^6 \) raised to the power of 3.
- According to the Power Rule, we multiply the exponents:
\[ (6^6)^3 = 6^{6 \cdot 3} = 6^{18} \]
So, the equivalent form of \( (6^6)^3 \) is \( 6^{18} \).
The correct response is \( 6^{18} \).