Which of the following is not a good example of a hierarchy likely to be modeled by inheritance?

____ handles outgoing email messages, determining the paths an email message takes on the Internet. ?

A. ?POP B. ?SMTP C. ?IMAP D. ?MIME

If a namespace is attached to the schema, only therootelement needs to be _____ in the instance document.

Fill in the blank(s) with the appropriate word(s).