Final answer:
The stone reaches the ground first because the air resistance is greater on the feather, causing it to fall more slowly than the stone.
Step-by-step explanation:
The reason the stone reaches the ground first when a stone and a feather are dropped simultaneously from a certain height is because of air resistance. The correct answer is B: Air resistance on the feather is more than that on the stone. In the absence of air, all objects would fall with the same constant acceleration due to gravity, regardless of their mass. This was famously demonstrated on the Moon by astronaut David Scott, where he showed a hammer and feather fall at the same rate in a vacuum. Consequently, the greater air resistance on the feather, which acts opposite to its motion, causes it to fall more slowly compared to the stone.