The correct answer is D. When the source goes into detail that you don't need
Step-by-step explanation:
If you quote a source you include the exact words of the author; this means you do not modify any of the words, which is recommended in case you want to preserve the word choice of the author, the information might be altered if you summarize or paraphrase, or if the quote is memorable.
On the other hand, when you paraphrase you use your own words to state the point of the author. A valid reason to do this is "when the source goes into detail that you don't need" because by paraphrasing you can focus on key ideas from the source rather than quoting all the words of the author. Also, this is recommended if the essence of the ideas is still preserved.