Answer:
Stratified random sampling.
Step-by-step explanation:
Startified random sampling is one that divides the total population into subpopulations and analysis of each subpopulation is done to measure variations between them.
Each subpopulation is adequately represented in the whole sample used for study. For example when a population bis divide based on age into 18-30 years, 31-50 years, and 51 years and above.
The researcher divides all the current students into groups based on their class standing (freshman, sophomores, etc.). Then, she randomly draws a sample of 50 students from each of these groups to create a representative sample of the entire student body in the school.
This is use of stratified random sampling.