Answer: c. Dr. Michaels administers a questionnaire to gather data on childhood friendships to a group of 5-, 6-, and 7-year-olds. She meets with all three groups and gives them the same questionnaire for the next 3 years and stops when they are 8, 9, and 10 years old.
Explanation:
A longitudinal study in research design can be define as the study which is associated with the repeated observation of the same kind of variable(s). Such variables are examined for the short and long periods of time. It is a type of observational study that can be structured as randomized experiments.
C. is the correct option this is because of the fact that the a single variable is used here that is friendship, to make it a longitudinal study with the same children that were assessed in different years of their age at different time duration.
