AP Physics B Practice Exam

A student hypothesizes that the mass of a substance affects how the temperature of the substance changes when it is heated. The student uses the following procedure to test the hypothesis:

Each sample is initially at room temperature before heating.
Each sample is heated for the same amount of time with the same heat source.
The final temperature is measured for each sample.

Which of the following would be the best way to select the samples for testing the student’s hypothesis?