To use the Product Rule of Exponents, we can apply the formula:
\[ a^m \cdot a^n = a^{m+n} \]
In your case, we have:
\[ (13)^6 \cdot (13)^3 \]
Applying the Product Rule:
\[ (13)^{6+3} = (13)^9 \]
Therefore, the equivalent form of \((13)^6 \cdot (13)^3\) is \((13)^9\).
The correct response is (13)9.