Which sentence crosses the required connector pairing after a fronted hardly or no sooner clause?
No sooner had the doors opened than the queue moved.
Hardly had the briefing begun than the alarm sounded.✓Bonne réponse
Scarcely had the rain stopped when the match resumed.
Hardly had we unpacked when the client arrived.
Explication
The faulty sentence pairs hardly with than, but the standard partner for hardly in this construction is when. No sooner pairs with than, so exchanging the connectors breaks the conventional pattern.