I'll suggest that you quote and link to the relevant part of the Help Center and add any additional information that may tie to the specific case of the question asked.
Our Help Center articles are designed to be pretty broad and not get too deep into edge cases; that's what our FAQ articles are for. Because of this, someone asking a question may get most of what they need from the Help Center article but not all of it. In many cases there's something small that might change the general answer.
Even if that's not the case, quoting the Help Center and restating the information that specifically relates to the question in an answer and linking to the Help Center is the right course of action. This has two benefits.
- The information is now on Meta - this isn't a bad thing. We don't index the Help Center in search, so if people are unaware of the HC, it can get missed easily.
- There are more links to the Help Center, which means more people may realize it exists and use it.
Both of these are good! Our poor Help Center has tons of information but is little-used because we don't make it really easy to find.
If the question is broad enough that it encompasses most of what's in the Help Center article, feel free to turn the entire question and answer into a FAQ but don't feel like the answer needs to specifically mirror the HC... we generally expect FAQs to be more detailed.