Answer:
quasi-experimental quantitative research ( longitudinal) comes to mind although observation ( could have) played an important role
Explanation:
If each of the chosen subjects would have had been chosen bearing in mind their individual characteristics, or their belonging to a certain predetermined group and the researche would have been based on observation, not just the test results and the conditions ( environmental) and personal would have been eentirely controlled by the researchers then the coordinates then the answer would have been different.