The diet of the ordinary Greek in classical times was largely vegetari

I'm not sure why you quote Ajitesh when you write "Not exactly!" when Ajitesh is the only expert in the thread who you seem to agree with! And Ajitesh is right -- there's nothing inherently wrong with using "and" at the end of a list, and then following that list with another "and". If I write: I mainly eat potatoes, pasta, and rice, and I eat fish on holidays, that's a perfectly good sentence. The whole purpose of the "and" I highlight in red is to indicate that the list is about to end, so we know that a subsequent "and" (the one in blue) is a conjunction joining the list to a second idea.

So I disagree with the many expert posts in this thread, including the top post, that dismiss B because of some blanket objection to using "and" twice. In answer B, the second "and" clearly does not continue the list, but instead joins it to a new idea, so we aren't using "and" twice in the same list (which we can't do). It's not a problem, and I agree with Ajitesh about that (and as far as I can tell, with no other expert in this thread). The problem I see with B comes down to meaning. When we describe meat as "rare", we usually mean "almost uncooked". To be sure the sentence does not convey that unintended meaning, we need to avoid phrases like "rare meat" or "meat was rare", and replace it with "and rarely included meat" or, "with meat on rare occasions", or, as answer E awkwardly does, "with meat as a rarity", so it becomes clear that meat was a rare inclusion in the diet, and not that the meat itself was rare.