change the food source use more than one squirrel increase the number of students shorten the period of observation
I gave my students this multiple choice question: A student conducts an experiment to determine the average size of acorn that squirrels eat. The student gave several different sizes of acorns to a squirrel. Which action would most likely improve the results?

Only one answer is correct among these 4 choices:
- change the food source
- use more than one squirrel
- increase the number of students
- shorten the period of observation

Could you tell me which one is correct?

use more than one squirrel