Final answer:
The slope of the line y = 0.25x + 15 represents the rate of change in dollars for each unit increase in x.
Step-by-step explanation:
The slope of the line y = 0.25x + 15 is 0.25.
In this context, the slope represents the rate of change in dollars for each unit increase in x.
Therefore, option D is correct.
The slope of 0.25 means that for every additional dollar x, the amount of money earned y increases by $0.25.
Learn more about slope in linear equations