We are asked to multiply \( a^{3} \cdot a^{-5} \). This involves using the laws of exponents.
Step 2: Apply the exponent rule
When multiplying terms with the same base, we add the exponents:
\[
a^{m} \cdot a^{n} = a^{m+n}.
\]
Here, \( m = 3 \) and \( n = -5 \), so:
\[
a^{3} \cdot a^{-5} = a^{3 + (-5)} = a^{-2}.
\]
Step 3: Simplify the expression
A negative exponent means the reciprocal of the base raised to the positive exponent:
\[
a^{-2} = \frac{1}{a^{2}}.
\]
Final Answer
The correct answer is:
\[
\boxed{\frac{1}{a^{2}}}.
\]