Great question. You're asking why the answer's (D) and not (A).
This is a strengthen with a sufficient premise question. Oscar doesn't think he's plagiarizing Ethel Myers' work because she told him he could use passages from her work without attribution.
Millie says that Myers can't give Oscar permission to plagiarize and that he's still committed plagiarism.
We're looking for an answer that, if true, would fully justify Oscar's reasoning. We need to make a bridge from his premise (he received permission) to his conclusion (that the article accusing him of plagiarizing is unwarranted). Let's take a look at the answers.
(A) says a writer has no right to quote passages from another published source if the author of that other source has not granted the writer permission to do so. This maps to
/granted writer permission - >/right to quote
the contrapositive of this is right to quote - >granted writer permission
The problem with (A) is that it doesn't bridge Oscar's premises and conclusion. In order to make (A) correct, we would have to switch the sufficient and necessary conditions of the statement so that it would say
granted writer permission - >right to quote
As it stands, however, this is not what is being said, and as (A) is written, it does not make Oscar's argument valid.
Now let's look at (D). (D) says that an author is entitled to quote freely without attribution the work of a writer if that writer relinquishes his or her exclusive right to the material. This maps to
relinquishes right - >quote freely
This is exactly the bridge we're looking for. "If that writer relinquishes his or her exclusive right to the material" maps to Oscar's premise of Myers giving him permission in private correspondence to do so, and "an author is entitled to quote freely without attribution the work of a writer" maps to Oscar's conclusion about the accusations of him committing plagiarism to be unwarranted. (D) bridges the gap between the premise and the conclusion, thereby justifying the argument. This is our correct answer choice.
Does this make sense? Let us know if you have any more questions!
