The following sentence has an error in it. Choose the part which has the error.
Hardly had / I reached the / crowded platform than / the guard waved his flag.

Correct option is C

The error lies in option (c) crowded platform than.
Detailed Explanation:
· The correlative conjunction “Hardly … when” is the correct pair.
· The sentence wrongly uses “than” instead of “when.”
Correct Sentence:
· Hardly had I reached the crowded platform when the guard waved his flag.
Grammatical Rule Used (English):
· Correct correlative pairs:
· Hardly … when
· No sooner … than
Grammatical Rule Used (Hindi):
· Hardly के साथ हमेशा when आता है, than नहीं।
Explanation of Other Parts:
· (a) Hardly had: Correct inversion.
· (b) I reached the: Correct verb form.
· (d) the guard waved his flag: Correct clause.