What the reader may infer about the historical period in which this story is set is:
C) It is a time when educational trends didn't favor whimsy.
According to the given story, the writer is talking about sticking to facts because he is of the opinion that one can only form "the minds of reasoning animals on facts".
He further mentions that he will bring up his children based on this "principle of facts" as sticking to facts are what is "only wanted in life".
These statements about the importance of sticking to facts as that is the only thing needed, suggests that the historical period the story was set is one where trends in education did not favor a person being whimsy.
A person who is said to be whimsy is one who is said to be fancy or with a great deal of humor.
