Error spotting (exam direction): Identify the erroneous part (A/B/C) — choose D if there is no error — 'The retiring principal asked his old pupils / to take the interest in the school / after he has retired. / No error.'

Given sentence parts (A–D)
A. The retiring principal asked his old pupilsB. to take the interest in the schoolC. after he has retired.D. No error.

Concept/Approach (idiomatic usage: 'take interest in')
The idiom is 'take interest in (something)', not 'take the interest in'. The article 'the' is incorrect here.

Step-by-Step correction
1) Replace phrase: 'to take the interest in the school' → 'to take interest in the school'.2) (Additional improvement) Sequence of tenses: 'after he had retired' fits better than 'has retired' because the asking occurred before the retirement; however, the tested error is in Part B.

Verification/Alternative
Compare: 'take interest in studies' (correct) vs 'take the interest in studies' (incorrect).

Common pitfalls
Adding a definite article to fixed idioms.

Final Answer
B — 'to take the interest in the school' should be 'to take interest in the school'.