Final answer:
The Apple operating system, known as macOS, has an advantage of being less susceptible to viruses compared to many of its counterparts due to its robust security, Unix-based foundation, and strict app store policies.
Step-by-step explanation:
One advantage of the Apple operating system compared with its counterparts is D. It is less susceptible to viruses. Apple's macOS is known for its robust security measures, which make it less vulnerable to malware and viruses than many other operating systems. This is due, in part, to the Unix-based foundation of macOS, its strict app store policies, and the fact that it's a less common target for hackers compared to Windows, which has a larger market share. While it's important to note that no system is completely immune, the perception and track record suggest that macOS typically experiences fewer issues with viruses.