In the sentence given below, replace the phrase 'all and one' to make the sentence grammatically correct. If the sentence is correct as it is, mark (d) as the answer. Whether I stay in Mumbai or Pune, it is all and one to me.

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