Your system has been acting strangely since you downloaded a file from a colleague. Upon examining your antivirus software, you notice that the virus definition file is missing. Which type of virus probably infected your system?
a. Polymorphic virus
b. Retrovirus
c. Worm
d. Armored virus
Answer: B
Retroviruses are often referred to as anti-antiviruses. They can render your antivirus software unusable and leave you exposed to other, less-formidable viruses.