The correct answer is (C) at.
The word “at” is used to indicate proficiency or skill in a particular activity. In this case, the speaker is saying that the blind man is very good at doing calculations.
The other options are not as accurate. The word “in” is used to indicate a location or position. The word “with” is used to indicate a tool or instrument. The word “about” is used to indicate a topic or subject.
Here is a more detailed explanation of each option:
- A. in
The word “in” is used to indicate a location or position. For example, you might say that someone is “in the kitchen” or “in the car.” In this case, the speaker could not have said that the blind man is “in calculations.” This is because calculations are not a location or position.
- B. with
The word “with” is used to indicate a tool or instrument. For example, you might say that someone is “writing with a pen” or “cutting with a knife.” In this case, the speaker could not have said that the blind man is “with calculations.” This is because calculations are not a tool or instrument.
- C. at
The word “at” is used to indicate proficiency or skill in a particular activity. For example, you might say that someone is “good at math” or “bad at dancing.” In this case, the speaker is saying that the blind man is very good at doing calculations.
- D. about
The word “about” is used to indicate a topic or subject. For example, you might say that you are “talking about the weather” or “thinking about your future.” In this case, the speaker could not have said that the blind man is “about calculations.” This is because calculations are not a topic or subject.