Answer:
The given situation is an example of cohort differences.
Step-by-step explanation:
A cohort study is a form of study that samples a group of people that performs a cross section at particular intervals through time. Such a group is called cohort and it shares a defining characteristic, generally the one which experiences a common event in a particular period like graduation or birth.
Example: studying the mathematical ability of two groups of adults born 50 years ago and 25 years ago and analyzing the cohort differences in the scores of the test.
Therefore, the given situation is an example of cohort differences