Answer:
Stratified data
Step-by-step explanation:
The given data in the question is an example of a "Stratified data"
A Stratified data is type of sampling of data or the random samples in which the collected data is divided into the sub groups of the same type or the same category.
Also,
The sample size of the subgroups in the Stratified data remains the same for every subgroup.
Here, the subgroups are
freshmen
sophomores
juniors
seniors
and the each have same sample size i.e 50