Looking at the slope of the "best-fit" line, you can see that for every two hours of homework, 15 more points are scored. (compare t=0 to t=2).
For t=5, the line seems to go through 47.5. So for t=7, which is two hours more, you'd expect a score of 47.5+15 = 62.5.
That answer is in the list, so I'd choose that.
In reality, you would never be able to have any score you like just by putting more hours in, so this can never be a straight line forever...
