Question does not say if the straight line is the least squares best fit line. Assuming it is, we still have the question whether Wilson's score vs hours spent per week is linear, as we do see some tendance of a decline of the rate of increase at the top of the the range, which means that the function COULD be parabolic or piecewise. The score could actually decrease if Wilson has difficulty doing the homework, to a point that he spent way over the expected time to finish relatively simple homework.
To sum up, the question is incomplete in supplying necessary information, perhaps on the part of the user posting the question, perhaps the school.
Anyway, back to the question, assuming a straight line relationship according to the given straight line, rate of increase per day = (50-15)/5=7 hours/week.
Therefore if Wilson spends 6 hours to do his homework, and assuming the score follows a straight line, he expects to get 50+7=57 points, an answer that is not one of the answer choices.
Perhaps the information is incomplete, perhaps there are other possible assumptions. That's the best we can do with the question as is.
