Final answer:
The y-intercept represents the starting point of the bunny fence on the vertical axis.
Step-by-step explanation:
The y-intercept, a, of the line describes where the plot line crosses the y-axis. In the context of Ms. Yelaska building a bunny fence, the y-intercept represents the starting point of the fence on the vertical axis. It tells us the value of the relationship when the x-coordinate is zero, which in this case indicates the initial position of the fence.