Answer:
Stratified random Sampling Method
Explanation:
The stratified random sampling is a sampling method that is used when working on a population that has different characteristics. The population is grouped according to who they are, the things they do in common, or what they have in common. These subgroups are called strata and it helps the researcher to get accurate result void of generalization.
The researcher in question, groups the population into a subgroup of 50 to get a more direct and accurate result, this method of sampling is the stratified random sampling method.