To simplify \( 5^{10} \cdot 5^{5} \) using the Product Rule of Exponents, which states that \( a^m \cdot a^n = a^{m+n} \), we can add the exponents:
\[ 5^{10} \cdot 5^{5} = 5^{10+5} = 5^{15} \]
So, the simplified expression is \( 5^{15} \).
The correct response is: \( 5^{15} \) (515)