To find out how many puzzles one student would complete, you can divide the total number of puzzles by the total number of students.
\[ \text{Puzzles per student} = \frac{\text{Total puzzles}}{\text{Number of students}} = \frac{80 \text{ puzzles}}{15 \text{ students}} \approx 5.3333 \]
Rounding 5.3333 to the nearest tenth gives you 5.3.
So, the correct answer is 5.3.