OK. So first, slope = rise/run. This can be calculated with any 2 points from the graph above.
I will use points (24, 168) and (8, 56).
Slope = (168 - 56) / (24 - 8)
Slope = 7
Since the y-intercept is 0, the equation is y = 7x
B should be the correct answer.
Cheers,
Brian