Answer:
This is an example of a longitudinal design.
Step-by-step explanation:
In social research, a longitudinal design is implemented to study the development of a particular pehnomenon across time, the main characteristic of this design is that the subjects of the study remain the same throughout the whole research and they are studied or observed at different points in time. Longitudinal designs are often used in psychology and have been very usefull in the construction of human development theories.
In this case, the characteristics of the research correspond with a longitudinal design.