Identify the segment in the sentence which contains a grammatical error.
If I was in his shoes, I would not have hesitated to take up the offer.

Correct option is B

Option (b) contains a grammatical error.
The correct expression should be "If I were" instead of "If I was". This is a subjunctive mood used to describe hypothetical or imaginary situations.
Correct sentence: If I were in his shoes, I would not have hesitated to take up the offer.
Grammatical rule used:
In conditional sentences (second conditional or unreal past), use “were” for all subjects (I/he/she/it/they/we) when expressing an unreal or imaginary situation.
Example: If I were you, I would apologize. (NOT "was")
Information Booster:
The subjunctive mood expresses wishes, hypothetical situations, or suggestions and is a formal structure not bound by normal subject-verb agreement.