When two stones of different masses are dropped simultaneously from the top of a building, both stones reach the ground together; option [C]. This phenomenon occurs due to the absence of significant air resistance, and according to the principle of universal gravitation, all objects fall at the same rate regardless of their mass. Therefore, neither the smaller nor the larger stone reaches the ground before the other. The composition of the stone does not affect this outcome. This concept is a fundamental principle in physics known as the equivalence principle, which states that in a vacuum, all objects experience the same acceleration due to gravity regardless of their mass. Thus, the correct option is [C] Both the stones reach the ground together, illustrating a fundamental aspect of gravitational physics.