To find the scale factor that Leo used to create the photograph of the original pentagon, we need to divide the length of the sides of the enlarged pentagon by the length of the sides of the original pentagon.
The original side length is 3 centimeters, and the enlarged side length is 8 centimeters.
The scale factor is calculated as follows:
\[ \text{Scale Factor} = \frac{\text{Length of enlarged side}}{\text{Length of original side}} = \frac{8 \text{ cm}}{3 \text{ cm}} = \frac{8}{3} \]
The scale factor that Leo used is \( \frac{8}{3} \).
Thus, the correct response is \( \frac{8}{3} \).