To simplify the expression \( 13^{-5} \cdot 13^{-11} \), we can apply the properties of exponents. Specifically, when multiplying like bases, we can add the exponents:
\[ 13^{-5} \cdot 13^{-11} = 13^{-5 + (-11)} = 13^{-16} \]
Next, we want to express this in terms of positive exponents. Using the property that \( a^{-n} = \frac{1}{a^n} \), we can rewrite \( 13^{-16} \) as:
\[ 13^{-16} = \frac{1}{13^{16}} \]
Looking through the provided options, the equivalent expression with only positive exponents is:
\[ \frac{1}{13^{16}} \]
So the correct response is:
Start Fraction 1 over 13 superscript 16 baseline end fraction.