Answer:
D. The plumber charges a flat rate of $75.
Explanation:
The vertical intercept is the point where the data intersects the vertical axis. The vertical axis will be the dependent variable, and the horizontal axis will be the independent variable.
In this situation, the total cost depends on how many hours the plumber works; this means that the total cost is the dependent variable, going on the vertical axis, and the number of hours is the independent variable, going on the horizontal axis.
The vertical intercept, since it is on the vertical axis, will be where the horizontal axis is 0. In this situation, this means the cost when the plumber has been there 0 hours; this is the flat-rate fee he charges, $75.