The answer is 13 you have to add the top and bottom
Check the picture below.
now, the "x" is a constant, the rocket is going up, so "y" is changing and so is the angle, but "x" is always just 15 feet from the observer. That matters because the derivative of a constant is zero.
now, those are the values when the rocket is 30 feet up above.

This one is best done by elimination:
We need to start 4 meters away, so B is clearly wrong.
We first move towards Mr. Wilson (i.e. distance is decreasing) so A is wrong.
Our speed is faster on the way back, so the two sloped section must have differing slopes, so D is wrong.
(D also doesn't start at 4, it's wrong for two reasons.)
Only C is left.
We can check each part to make sure. First we start at 4m, then move away, then stay still (zero slope) for three seconds, then move back faster (higher slope). All parts check out ok.
I believe the answer is C - 60 inches. 60 x 2 = 120, which is both lengths, and since he width is half the length, then 30 x 2 = 60. So 130 (length) + 60 (width) = 180. So 60 inches would be the maximum length for both sides.