Having undergone extensive repairs, the engineers launched the bridge, which had been damaged by the recent earthquake, back into service ahead of schedule.
Correct: B
The introductory participial phrase 'Having undergone extensive repairs' must logically modify the subject of the main clause. In the original sentence (A), this phrase modifies 'the engineers,' incorrectly implying that the engineers, not the bridge, underwent repairs. This is a classic dangling modifier error. Option B corrects this by making 'the bridge' the subject of the main clause, so the phrase 'Having undergone extensive repairs' correctly refers to the bridge. It also maintains conciseness and clarity. Option C places the modifier at the end, making it ambiguous about what 'having undergone' refers to. Option D is grammatically awkward and verbose. Option E uses 'After undergoing extensive repairs,' but the subject of the main clause is still 'the engineers,' so the modifier still dangles.