To determine the correct equation and whether the relationship is proportional or nonproportional, let's analyze the data provided:
- When \( x = 0 \), \( y = 0 \)
- When \( x = 1 \), \( y = 125 \)
- When \( x = 2 \), \( y = 250 \)
- When \( x = 3 \), \( y = 375 \)
- When \( x = 4 \), \( y = 500 \)
From this, we can see that as \( x \) increases by 1 hour, \( y \) increases by 125 parts. This suggests a linear relationship.
To form the equation, we notice:
- The slope (rate of production) is 125 parts per hour.
- When \( x = 0 \), \( y = 0 \) which suggests that the equation starts from the origin.
This leads us to the equation:
\[ y = 125x \]
Since this equation goes through the origin (0,0) and has a constant rate of change, it is a proportional relationship.
Thus, the correct answer is:
\[ y = 125x, \text{ proportional.} \]