Answer:
C: while
Step-by-step explanation:
The word "while" logically completes the sentence because in the first sentence, we read about what Dr. Hermit believes, and in the second sentence, we read about Dr. Samsa opinion, which is contrary to Dr. HermitĀ“s. The conjunction 'while' (compared to the fact that; but) is the best option because it is used to emphasize a contrast.