If you are logged on to Windows Live Messenger, why would you be unable to engage

in an instant messaging session with your brother, who is logged on to his AOL

Instant Messenger account?

a. Because you use Windows and your brother uses Apple OS X

b. Because Windows Live Messenger has built-in security and AOL Instant

Messenger does not

c. Because AOL Instant Messenger and Windows Live Messenger use their own

proprietary protocols

d. Because AOL Instant Messenger encrypts