A friend has called you about a possible computer problem because her computer is acting
strangely. Sounds play unexpectedly, the monitor turns off suddenly, the hard-drive light
flashes constantly, the computer sometimes reboots itself without warning. When you
inspect your friend’s system, you notice that several ports are open. Which of the following
is most likely the cause of these symptoms?

A.
The computer has been infected by a worm.

B.
The computer has been infected with an illicit server.

C.
The computer has been infected with a polymorphic virus.

D.
The computer is experiencing a denial-of-service attack.