to include additional variables in the experiment to complete the steps of the experiment in less time to find a less expensive way to conduct the experiment to increase the likelihood of accurate experiment results
I gave my students this multiple choice question: Why do scientists perform multiple trials of the same experiment?

Only one answer is correct among these 4 choices:
- to include additional variables in the experiment
- to complete the steps of the experiment in less time
- to find a less expensive way to conduct the experiment
- to increase the likelihood of accurate experiment results

Could you tell me which one is correct?

to increase the likelihood of accurate experiment results