To determine if the relationship is proportional, we need to check if the ratio of calories burned to time walking is constant for all the given values.
We can calculate the ratio for each pair of values in the table:
- For 20 minutes: \( \frac{100 \text{ calories}}{20 \text{ minutes}} = 5 \)
- For 30 minutes: \( \frac{150 \text{ calories}}{30 \text{ minutes}} = 5 \)
- For 40 minutes: \( \frac{200 \text{ calories}}{40 \text{ minutes}} = 5 \)
- For 60 minutes: \( \frac{300 \text{ calories}}{60 \text{ minutes}} = 5 \)
- For 80 minutes: \( \frac{400 \text{ calories}}{80 \text{ minutes}} = 5 \)
Since the ratio (calories per minute) is constant (5 calories per minute) and the graph passes through the origin (0 minutes, 0 calories), the relationship is indeed proportional.
Thus, the correct answer is:
The relationship is proportional.