Chan Hee is inflating a basketball using an air pump. He notices that the pump gets warm as he uses it. What is a good hypothesis that could lead to new experimentation?

A good hypothesis makes a testable prediction about the observation. Choice C predicts that squeezing air more will make it hotter, which can be tested by changing how much the air is compressed and measuring its temperature. The other choices are opinions or general statements that do not explain why the pump warms up.

AI-written and checked against the verified answer.