Answer:
The description corresponds to an observational study.
Explanation:
In Observational studies, researchers observe the effect of a risk factor without changing what is exposed to it or its conditions. On the other hand, in an experimental study, researchers can introduce a change and study the effects of it.
(I’m not a professional) but I would say that D would be a possible answer because it tests and shows what they (the interviewee) is interested in. Whether it’s for the money or the easy work etc.
This is not true! There are many other such factors.
One of them is similar to food: the availability of water.
Other is also natural disasters: tsunamis, earthquakes... they also limit population from time to time. Similarly diseases such as Aids.
