Select the most appropriate option that can substitute the underline word in the given sentence. If there is no need to substitute it, select ‘No substitution’. Rohit had hardly stepped into the office than he was summon by his boss.

Correct answer: when he was summoned

Explanation: The correct answer is C. ✅ After "hardly", the correct structure is "Hardly had... when...", not "than". Also, "summon" is incorrect here; it should be "summoned", the past participle form. Correct sentence: Rohit had hardly stepped into the office when he was summoned by his boss. "Than" is used with comparisons, not after "hardly." "Summon" is the base form; the past participle "summoned" is needed. "Then he were summoned" is incorrect in both structure and verb agreement.