Scientists analyze all results. Scientists use safety precautions. Scientists conduct experiments once. Scientists change at least two variables.
I gave my students this multiple choice question: Scientists perform experiments to test hypotheses. How do scientists try to remain objective during experiments?

Only one answer is correct among these 4 choices:
- Scientists analyze all results.
- Scientists use safety precautions.
- Scientists conduct experiments once.
- Scientists change at least two variables.

Could you tell me which one is correct?

Scientists analyze all results.