In bold face questions, as we read the question stem, its important to understand what each statement is doing while understanding the entire argument.
Here is some pre-thinking I did for the roles played by BF statements:
After reading the entire question stem, I quickly break down the structure- Two people developed some similar concepts. Traditional opinion is offered that the developers developed these concepts independently (without referring to each other's work). Then, historians's views are presented by the professor and evidence is offered that supports historians' view.
The first BF statement does exactly this. It provides evidence/information that supports the conclusion/view of historians.
Then, the statement comes "However, the discovery warrants..."- this is professor's own view/conclusion. And then the second BF statement offers evidence that supports his own view as to why this discovery of Russel's notes needs more understanding.
Now, once we are sure we understand this structure, moving on to answer choices:
A. the first part itself is incorrect, I wouldn't even read further- The first BF statement is evidence that supports the historians' conclusion and the professor's conclusion is actually against the ones offered by the historians. So it can not support professor's conclusion
B. Again, incorrect for the same reason as above
C. Correct- exactly matches with the prethinking
D. the first part itself is incorrect - There is no intermediate conclusion. There is historians' view and evidence to support it and counter argument of professor and evidence to support his position
E. The second part is incorrect (first is correct)- Second BF statement does not support the evidence offered by the first BF statement. It is actually counter evidence to it.