Sentence Correction Homework Question Bank: Nightshades

[saurabhmalpani]

Hello this question (Labeled: Nightshades) is from the MGMAT HW question banks. I am not posting the complete question as I don't want any copyright issues.

Original Question

Though now eaten in large quantities around the world and harmless, the tomato is a member of the generally toxic nightshade family, including belladonna, and was once thought to be poisonous itself as a result

The correct option:
Though now eaten in large quantities around the world and known to be harmless, the tomato was once considered poisonous because it is a member of the generally toxic nightshade family, which includes belladonna.

Explaination given: The original sentence is wrong because of................And Also, the phrase "though now eaten in large quantities around the world and harmless" contains two elements that are not parallel.

My question here is why these two items are not parallel. And what makes them parallel in the Correct option.

[JonathanSchneider]

Structurally, "eaten" and "harmless" are fairly similar. They are both adjectives. Of course, "eaten" is technically a participle, functioning as an adjective, and so "known" (a participle) is even closer structurally. The more important point here is the logical parallelism. We have: "now eaten ... and harmless." But are the tomatoes only just now harmless? No, they've always been harmless. It's only that they are "now ... known" to be harmless.