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.
