Answer:
D.
Explanation:
7.99 is the basic fixed cost per month. this is charged, even if there are no songs (x = 0) downloaded.
and so, 1.75 is the cost per downloaded song in addition to the basic fixed cost. so, yes, the number of downloaded songs has to be multiplied by the cost for a single song to get the total.
and so, 1.75 is the change in the total cost for every automakers download (every time x is increased by 1).