Correct Answer: Polymorphic virus

Solution : The correct answer is Polymorphic virus.

To prevent detection by antivirus software, polymorphic viruses vary each time they are installed. This is accomplished by encrypting its code and employing different encryption keys each time. This makes detecting and removing polymorphic malware challenging for antivirus software. Polymorphic viruses are malware that is intended to be difficult to detect and eradicate.