We would need more information, are you sure this is all there is?
With the information that is given I believe that the answer is:
C. Constantly changing pieces of literature.
I think D
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This should be true. Scientists very often have the idea of self-censure because they understand whether or not their research could be potentially dangerous, for example, if they understand that their creation could be a terrible weapon they decide to not pursue it and abandon the research. Things get nasty when they don't do it, but almost anything can be exploited so they sometimes don't even understand in what ways their research could be exploited. If ideology starts banning scientific research because of ideological differences, then it's similar to how the church killed scientists in the medieval era because scientists opposed what was essentially ideology at the time.
" For his father was as strong as an ox and as stubborn as a mule." is an example of direct characterization
