Debating with physics teacher.

[FrankJ]

At best a poorly worded question. It would be better as a short answer, but in that case any could be correct with the right reasoning. The best answer is B the heavier rock. For a given velocity air resistance is independent of mass. Air resistance is a function of the cube of the velocity. Since the heavier rock has greater force of gravity acting on it, it will have a greater terminal velocity thereby a greater force from air resistance.

Or once again at terminal velocity: do a force balance
F=MAg = F(air resistance). Since the more massive rock has a greater force from gravity, the counteracting force from air resistance will be greater. At less than terminal velocity, the more massive rock will have a greater acceleration, but at any given velocity the force from air resistance will be the same on both rocks. A=(MAg-F(air resistance))/M

If you measure the acceleration of the rocks and the terminal velocities, the effect of the air resistance might seem to be greater on the lighter rock since it will accelerate slower & have a lower terminal velocity, but that was not the question was it?
F=force, M=mass, Ag= acceleration of gravity, F(air resistance) Force as a function of air resistance