Answer:
A. need
Explanation:
It is the one that flows best when speaking the sentence out loud.
1 = I don't think the mail has arrived yet.
2 = Nobody has bought him a present yet. (?)
3 = We have been here for forty minutes already.
Lol I hope this helps- About the second one, I didn't know whether or not it was correct, but I think all the others are!
