Good question, and one I'd like to see discussed more too. From my point of you, your point "a)" is the one I never choose. In my opinion, one could rarely writ

Good question, and one I'd like to see discussed more too. From my point of you, your point "a)" is the one I never choose. In my opinion, one could rarely write something for that audience which might be novel to them. Perhaps I'm just not that smart, but to me, when I picture the true masters in my field, I rarely need to communicate anything to them that they haven't figured out for themselves already, and in the rare case that I might, those types of people don't mind a bit of revisiting of the fundamentals anyway. My favourite type of writing is one that also comes in handy to myself a couple of years down the line, which inevitably involves a modicum of handholding and starting from some fundamentals. So I'd say most of the articles should be b) or c).