Topic: Conjunction,

Best Answer Explained in Below-:

The correct choice for the sentence is "C) Although." This conjunction is used to introduce a contrast or exception, setting up a scenario where one condition exists alongside another that might typically prevent it. In the context of the sentence, it highlights the unexpected nature of the doctor performing emergency surgery despite it being a holiday.

If we analyze the other options:

- "A) During" would imply that the surgery was performed at the same time as the holiday, but it does not capture the contrast intended in the sentence.

- "B) Even" suggests emphasis but fails to connect the ideas in the context of contrast or surprise.

- "D) So" indicates a cause-and-effect relationship, incorrectly suggesting that because it was a holiday, the doctor performed the surgery, which doesn’t fit the situation described.

By using "Although," the sentence effectively communicates that performing emergency surgery is not typical behavior during a holiday, hence emphasizing the doctor's dedication and the urgency of the patient's condition. This contrast is fundamental to understanding the situation being presented.