As soon as the doctor opened the heart for surgery, he found the tricuspid valve out of order.
Which of the following transformations is correct ?

The correct answer is Option B (No sooner did the doctor open the heart for surgery than he found the tricuspid valve out of order.).

Key Points:
• This question evaluates the candidate's proficiency in Sentence Transformation, specifically using correlative conjunctions, a frequent topic in MPSC exams. Mastering the 'No sooner... than' structure is essential for grammatical precision.
• Option 2 is the correct answer according to the official MPSC answer key. The structure 'No sooner + auxiliary verb (did) + subject + base verb (open) ... than ...' correctly transforms the original past-tense sentence while maintaining chronological accuracy and syntactic validity.
• Let us analyze why the other options are grammatically flawed. Option 1 incorrectly pairs 'Scarcely' with 'then' (it should be 'when') and lacks inversion ('did the doctor open'). Option 3 uses the past tense verb 'opened' after 'did' (a double past error) and incorrectly uses 'then' instead of 'than'. Option 4 incorrectly uses the present auxiliary 'does', contradicting the past tense context established by 'found' in the main clause.
• A common MPSC trap is confusing 'then' with 'than' or using V2 (past tense verb) after 'did'.
• Remember the exact formula: No sooner + did/had + Sub + V1/V3 + than.
• Key Takeaway: Remember: The correct structure is 'No sooner + did + Subject + V1 + than...' OR 'No sooner + had + Subject + V3 + than...'. Never use 'then'.