To solve the equation \( 3^{-2x+1} \cdot 3^{-2x-3} = 3^{-3} \), we start by using the properties of exponents.
First, we can combine the exponents on the left-hand side:
\[ 3^{-2x+1} \cdot 3^{-2x-3} = 3^{(-2x+1) + (-2x-3)} \]
Now we simplify the exponent:
\[ (-2x+1) + (-2x-3) = -2x - 2x + 1 - 3 = -4x - 2 \]
Thus, the equation becomes:
\[ 3^{-4x-2} = 3^{-3} \]
Since we have the same base, we can set the exponents equal to each other:
\[ -4x - 2 = -3 \]
Now, solve for \( x \):
- Add 2 to both sides:
\[ -4x = -3 + 2 \]
\[ -4x = -1 \]
- Divide by -4:
\[ x = \frac{-1}{-4} = \frac{1}{4} \]
So, the solution for \( x \) is:
\[ x = \frac{1}{4} \]
Esmeralda should select \( \frac{1}{4} \) as the final answer.