Final answer:
Myra would use source code from older malware to develop new malware and remove some functions to evade heuristic detection by antivirus systems, making the new malware harder to identify.
Step-by-step explanation:
Myra could use source code belonging to older malware to develop new malware and remove some of its functions mainly to keep the malware undetected through heuristic checks. Heuristic checks are methods used by antivirus software to detect new, previously unknown viruses or new variants of known viruses. By using code from older malware that might be already recognized by security software, and modifying or removing certain parts of it, developers of malware can effectively create a new threat that is harder for heuristic algorithms to detect because it only partially matches the signatures of known threats.
Furthermore, by removing some functionality, the malware can become smaller and simpler, which often means it will operate faster and require fewer resources. This can also contribute to its ability to evade detection, as larger and more complex malware might be easier to spot. Another potential benefit is that with less functionality, there's less code that might trigger antivirus software heuristics or behavior monitors.
Therefore, the correct answer to why Myra would use source code of older malware and remove some of its functions is D) To keep the malware undetected through heuristic checks.