Final answer:
Red Hat is best described as the most 1) popular commercial Linux distribution, favored for its robust support and extensive training in enterprise settings.
Step-by-step explanation:
The student asked which descriptor best fits the commercial distribution of Red Hat.
The most suitable answer is that Red Hat is likely the most 1) popular commercial distribution of Linux, especially in enterprise environments.
Red Hat Enterprise Linux (RHEL) is known for its robustness, security, and extensive support.
Red Hat also offers a strong support system and extensive training which makes it a popular choice among businesses.
While Red Hat might also be considered stable and secure, these labels could apply to several distributions, and without current pricing details, it's challenging to definitively say it's the most expensive option.