Choose the correct alternative which can be substituted for the below-underlined phrase.
The parents attending the meeting were hostile and aggressive. This set the mood of the unfortunate meeting.

He became rich overnight. What part of speech is 'overnight'?

The nightingale is a singing bird. In this singing is a/an --

I Came home after the rain -----.

The Doctor took the round in the hospital. Here 'round' is a/an ---

Alumni is the plural from of