Which of the following are indications of a virus attack on a computer? Each correct answer
represents a complete solution. Choose three.

A.
Although the computer has sufficient memory, an out-of-memory error message is displayed.

B.
The applications installed on the computer system work properly.

C.
An antivirus program is not able to run.

D.
The computer runs slower than usual and stops responding.

Explanation:
A virus is a program that can do the same things as other programs. The only major difference is that
it attaches itself to other programs. It executes secretly when the host program is run. A computer
virus can corrupt or delete data on a computer. Even it can delete all content of a hard disk and can
move to another computer through any media such as pen drives, floppy drives, e-mail attachments,
etc.
Some indications of a virus attack are as follows:
The computer runs slower than usual and stops responding.
The applications installed on the computer system do not work properly and the computer restarts
on its own.
Disk drives cannot be accessed.
An antivirus program is not able to run, and unusual error messages are displayed.
An attachment is opened having double extension, such as .jpg, .vbs, .gif, or .exe.
Although the computer has sufficient memory, an out-of-memory error message is displayed.
Task Manager or Command Prompt cannot be started.
The computer virus can reformat the disk and change the file settings.