What are your thoughts??

Extraneous variables are those variables that are unknown or unforeseen at the start of a study that has a bearing on the results of the study.
Methods used to control extraneous variables:

Making sure that the samples are random ensures that the extraneous variables are standardized across the different groups. This makes it so that the effect of the extraneous variable becomes reduced than in cases where the extraneous variable is present only in certain sections of the sample (Behi