For the following, pick all that apply.

In the past few days I have had four e$-$mail messages bounce back as undeliverable. They were sent to different people. One was a new contact, one was a reply to someone who e$-$mailed me$,$ and the other two were people I e$-$mail frequently. Of those two, one message had an attachment; none of the others did. They all had AOL addresses, though. AOL must be blocking my messages.

Question $22$Answer

a$.$

Method of agreement

b$.$

The cause: emails bounced.

c$.$

The cause: AOL

d$.$

Method of difference

e$.$

Method of residue