the height from which the rocks are dropped the average time it takes the rocks to fall the density of the rocks the mass of the rocks
I gave my students this multiple choice question: Students dropped different rocks into sand to simulate meteorite impacts. Their goal was to determine which rock made the deepest crater. Which variable should the students control in order to have the most accurate results?

Only one answer is correct among these 4 choices:
- the height from which the rocks are dropped
- the average time it takes the rocks to fall
- the density of the rocks
- the mass of the rocks

Could you tell me which one is correct?

the height from which the rocks are dropped