Ricardo and Maria conducted an experiment to test if the mass of a ball affects how fast it would roll down a ramp. They set up the experiment using a ramp and three balls of different masses. They tested each ball once and recorded their results. They concluded that the more mass a ball has, the faster it will roll down the ramp. Why is this experiment not reliable?


Their experiment was not controlled.


Their experiment did not test enough variables.


Their experiment was not performed multiple times.


Their experiment was not performed by multiple people.