Stephen is on a ladder picking apples from a tree. He grabs for two apples but misses them. They fall and hit the ground at the same instant. What can Stephen conclude?

Responses

1) Air resistance must not affect the apples.
2) The apples must have the same weight.
3) The apples must have the same mass.
4) Gravity causes both apples to fall at the same rate.

4) Gravity causes both apples to fall at the same rate.