Marcel conducts an experiment to test which stain remover works best on mustard stains. he wants to make sure that he does not make mistakes and has correct data in his experiment.

what should marcel do to make sure that his data are correct?

conduct a similar experiment with a different washing machine
ask other students to conduct related experiments at their homes
ask his sibling to conduct the same experiment using his washing machine
repeat the experiment several times with the same variable and constants