Question

Choose the correct option to fill in the blank: She is good $\dots$ mathematics.

• A. in
• B. on
• C. at
• D. with

Hint:

Phrasal verbs and idiomatic expressions often dictate preposition usage. Skill or competence always takes the preposition 'at' (e.g., adept at, talented at, poor at).

Answer 1

The Correct Option is C

The phrase "good at" is the standard idiomatic expression used to indicate proficiency or skill in a particular subject or activity.
The correct grammatical usage is: $\text{Subject} + \text{is/are} + \text{good/bad} + \text{at} + \text{skill/subject}$.
Therefore, the correct preposition is "at".