repeating the experiment three times experimenting with multiple substances writing out the procedure after the experiment using three types of thermometers in the experiment
I gave my students this multiple choice question: A scientist is performing an experiment to determine the melting point of a new substance. Which action could increase the likelihood of obtaining accurate results?

Only one answer is correct among these 4 choices:
- repeating the experiment three times
- experimenting with multiple substances
- writing out the procedure after the experiment
- using three types of thermometers in the experiment

Could you tell me which one is correct?

repeating the experiment three times