C- By focusing on topics that are controversial
I would say the correct answer is that has an undetermined answer.
If a subject has been thoroughly covered, then there is no need for this researcher to do it all over again. If it's impossible to answer, there is no need to try. If it can be answered easily, then it doesn't really require a research. This leaves us with the last option, because a researcher might want to try and determine the answer.
Answer:
third option - the ingenuity of German design was apparent even when quality materials were unavailable.
Explanation:
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He was a epic hero. he is the same in the story