Which is the best description of a computer virus?

The best description of a computer virus is. Someone first starts out making a malicious program, then can send it to a unexpected user. After that, when the user opens the malicious program, it can do negative things on the target. The virus first starts out in the system32, then infects a random file type for example, exe files, or dlls etc. Then random errors can pop up on the computer saying "YOUR COMPUTER IS UNDER RISK! CALL THIS NUMBER NOW! 555-555-5555" and the options of the error, can direct you to a website, that can give you another virus. To get rid of a virus, you have to ignore the popups that comes onto your computer, and get a strong antivirus like avast, or avg. Then let it scan the system. After when the scan is done, it will show up the virus, and it will give you options "to delete virus or ignore it" you would hit delete. I hope this answer helped you. Let me know if you have any more questions! Thanks!

You forgot to add the possibilities. we don't know the options from which to choose.