Based on its context, which is the most precise meaning of the underlined word? No one would have believed in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's and yet as mortal as his own; that as men busied themselves about their various concerns they were scrutinised and studied, perhaps almost as narrowly as a man with a microscope might scrutinize the transient creatures that swarm and multiply in a drop of water. A. Examine carefully B. Question C. Take apart D. Magnify

I would say that the answer is a extreamely careful

According to the relation between all the options, the "underlined" word must be either scrutinised or studied. The correct answer is option A. Examine carefully.

The text is clearly about the Observation of alien beigns over humanity. In the context, scrutinise serves a similar function as study - as they are used together in a sentence: " ... that as men busied themselves about their various concerns they were scrutinised and studied ... ". The aim is to describe men as subjects being analyzed and observed from a considerable distance.

As for the rest of the options, they are all out of context:

B. To question would mean to study a subject directly or in close inspection, using speech as a tool.

C. To take apart would mean to study a subject by means of surgery.

D. To magnify would simply mean to enlarge the appearance of an object, not necessarily in order to study it.