【单选题】

Melissa and LoveLetter made use of the trust that exists between friends or colleagues. Imagine receiving an (46) from a friend who asks you to open it. This is what happens with Melissa and several other similarE-mail (47) . Upon running, such worms usually proceed to send themselves out to email addresses from the victim’s address book, previous emails, web pages (48) .

As administrators seek to block dangerous email attachments through the recognition of well-known (49) , virus writers use other extensions to circumvent such protection.Executable (.exe)files are renamed to. bat anD、cmd plus a whole list of other extensions and will still run and successfully infect target users.
Frequently, hackers try to penetrate networks by sending an attachment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwords and give the (50) access to your network.
A、attachmentB、packet
C、datagram D、message