The correct answer is B) No.
Curtis is not committing academic dishonesty in writing his essay because although he copies and pastes a sentence into his essay, he makes sure to include quotation marks and properly cites his source.
And that is precisely what teachers are asking their students. To properly cite the author, the book, the magazine or whatever reference they use.
The other option is that the student check any source, book, magazine or encyclopedia, understand the idea and write in its own words. That way he is avoiding plagiarism. There are some plagiarism software checkers that the student can use to doublecheck its work before submitting it.