Final answer:
The main idea of "A Sweet Invention" is that Ruth Wakefield was a cook who invented the first chocolate chip cookie.
Step-by-step explanation:
The main idea of "A Sweet Invention" is that Ruth Wakefield was a cook who invented the first chocolate chip cookie. The passage discusses how Wakefield accidentally developed the cookie by adding chopped chocolate to her cookie dough and the success it achieved. It also mentions the Toll House restaurant, but it does not state that the Chocolate Crunch Cookie was the first cookie served there, so option D can be eliminated.
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