---You were brave enough to raise objections at the meeting---Well, now I regret that.

---You were brave enough to raise objections at the meeting.
---Well, now I regret that.
A. to do b. to be doing C. to have done D. having done

解析：本题考查regret的用法。句意：我现在后悔在会上提出了反对意见。表示对已经发生的事情“后悔”应用regret doing ／having done。

就是这个解释