I just found this: the critical angle is the angle at which the refracted ray will travel along the boundary between the two media. So technically, the refracted ray is kind of in between the two media. However, remember there is also a partially reflected ray (which will obey the law of reflection i.e. angle of incidence = angle of reflection). The partially reflected ray will be much stronger than the refracted ray at the critical angle. The pip question c) is asking about the partially reflected ray.