Final answer:
In an elevator, the relationship between the magnitudes of the forces depends on the situations. If two blocks are stacked on top of each other, the upper force is greater than the lower force. If the blocks have the same mass, the forces will be equal. If the masses are different, no relationship can be determined.
Step-by-step explanation:
The correct relationship between the magnitudes of the two forces depends on the situation:
a) When two blocks are stacked on top of each other in an elevator, the upper block exerts a greater force on the lower block due to gravity, so the upper force is greater than the lower force (c).
b) If the two blocks have the same mass, then the forces between them will be equal and the magnitudes of the forces will be the same (a).
c) The magnitude of the force between the two blocks is determined by their masses, not the elevator, so no relationship can be determined (d).