Question About WANs

Hello r/networking.

So, I'm about to take the Net+ exam and feel 95% confident I will pass. This post isn't asking for advice in that regard (yes, I read the sidebar).

What I have is a more theoretical or abstract question that every single study resource I've used doesn't seem to address -- or I'm just not understanding the text.

Here It Is: When we talk about Wide Area Networks, are we talking about a) a dedicated and private connection between, e.g., Office A in LA and Office B in NYC; b) the whole of the internetwork that exists on the other side of every private network; c) a combination / something in between / something else entirely.

None of my study resources give any context whatsoever to their discussion of WANs. And I have no real IT experience. So context would be so, so helpful in helping me get my head around this one aspect.

Thanks!