about the usage of "at present" and "in the present" [closed]

Solution 1:

'In the present' is not used quite correctly in either B or D. It is a phrase used frequently when discussing tenses, but 'Today' or 'In the present day' might be better here.

So A and C are - slightly - better than B and D.

Unfortunately 'At present' is not quite right either. "At present we can see the fossils of them in the museum" sounds as if you are in the museum with the fossils in front of you. 'At present' - like 'At the moment' - suggests something more immediate, more fleeting than is required. "Today we can see the fossils of them in the museum" is more colloquial and suggests a broader period of time.