changing at a constant rate. nearly equal in several trials. being compared to a control. observed at one point in time.
I gave my students this multiple choice question: A line graph is best used when the measured variable is

Only one answer is correct among these 4 choices:
- changing at a constant rate.
- nearly equal in several trials.
- being compared to a control.
- observed at one point in time.

Could you tell me which one is correct?

changing at a constant rate.