To identify the set with the stronger interaction between the charged objects, the student should ask:
Are the objects both positively charged or both negatively charged?
This question directly relates to the nature of the interactions between the charges. According to Coulomb's Law, like charges repel and opposite charges attract; thus, knowing whether the charges are the same or different can help determine the strength of the interaction. The other questions regarding size, distance, and mass do not directly address the specific interactions between the charged objects.