Which principle describes a polymorphic virus's ability to avoid detection?

The principle that best describes a polymorphic virus's ability to avoid detection is encryption. Polymorphic viruses employ encryption techniques to change their signature each time they infect a system. By encrypting their code and changing the decryption routine with every iteration, these viruses can effectively mask themselves from traditional signature-based antivirus detection systems. This method allows them to evolve and evade recognition by security software, making them particularly challenging to identify and combat.

In contrast, self-replication refers to a virus's ability to make copies of itself, which is a characteristic of many types of malware but not specifically related to the evasion techniques used by polymorphic viruses. Data exfiltration is concerned with malicious actors stealing sensitive information from systems rather than avoiding detection. Stealth operations may encompass various tactics to avoid detection, but in the context of polymorphic viruses, the key mechanism through which they achieve this is encryption.