Answer:
(a) This is an observational study.
Step-by-step explanation:
Based on this information we can say that this is an observational study. The researchers in this scenario are not interfering with the choices that each individual is choosing or even with the overall environment. They are simply observing the actions taken by each individual and then collecting the data by asking them some questions. The entire process of this study would fall into the category of being an observational study.