We arrived at the conference. Then we realized that our reports were still at home

A. No sooner had we realized that our reports were at home than we arrived at the conference.

B. Only after we arrived at the conference did we realize that our reports were still at home.

C. Not until we arrived at the conference that we realized that our reports were still at home.

D. Hardly had we arrived at the conference that we realized that our reports were still at home.