This scenario precisely matches polymorphic malware, a type of advanced malware described in CEH v13 Malware Threats. Polymorphic malware dynamically alters its code, encryption, or signature each time it propagates, allowing it to evade traditional signature-based antivirus detection.

Additionally, the malware’s ability to remain dormant until triggered indicates logic-based activation, which is common in advanced threats designed to avoid sandbox detection.

CEH v13 emphasizes that polymorphic malware cannot be reliably detected using static signatures. Instead, organizations must rely on behavior-based detection, heuristic analysis, and advanced threat protection systems capable of identifying suspicious runtime behavior.

Options A, C, and D do not match the described behavior. Adware focuses on advertising. Worms self-propagate aggressively. Rootkits focus on stealth and persistence, not code mutation.

Therefore, Option B is the correct answer.