Answer:
b. observational study
Explanation:
Observational studies are commonly used in order to know the effects of a treatment or drug. This study recruits people (the population of interest) to participate and these people are then interviewed and observed on a face-to-face visit. This allows clinical investigation regarding the safety of the new medication, including its side effects and adverse effects. So, this allows the researcher to know the symptoms of the new drug including whether it can reduce migraine to people.
The study also allows the employment of different designs, thereby paving way to a better patient care.
