write a brief report repeat the experiment purchase new equipment make a data chart
I gave my students this multiple choice question: When performing a new experiment for the first time, a scientist reaches an unexpected conclusion. What must the scientist do in order to have the conclusion accepted by other scientists?

Only one answer is correct among these 4 choices:
- write a brief report
- repeat the experiment
- purchase new equipment
- make a data chart

Could you tell me which one is correct?

repeat the experiment