In a typical e-mail address, the "host" is
a. cpu processor 2500
b. the computer that houses an internet connection
c. an account designated by a user name
d. the receiver of an e-mail message.

The answer is most likely (b.) the computer that houses an Internet Connection.

In Computer Systems, host refers to the computer that has two-way access to other computers on the internet. In short, hosts are the computer servers or the mail servers. So if you are using an email address such as gmail and ymail, your emails host is on Google and Yahoo.