For any linear function
[tex]y=mx+b[/tex]
The slope "m" represents the change of y every time x increases one unit.
In this case, the variable in the x-axis is "the number of songs" and the variable is the y-axis is the "total cost per month"
The slope of the line represents the increase in the service cost every time a new song is downloaded.
The correct option is D. How much does the streaming service charge per downloaded song.
