Answer:
C
Explanation:
The error that the student made was to place the containers for the different fruits in different areas around the school.
In order to ensure that each contain receives the same treatment, they should have been placed in the same area around the school. Different areas around the school might have varied populations of fruit flies, hence, jeopardizing the result.
The containers should have been subjected to the same conditions in order to ensure an unbiased outcome.
The correct option is C.