The correct answer is The page number only
Since you've already mentioned who the author is, you don't have to mention him again. The book title would only be added if you're using multiple sources from the same author. If only one, then the page number only.
If you're asking for main idea, the main idea or thesis statement sentence is sentence 1, where they explain what the passage is about.
Answer:
roses are red (a)
violets are blue (b)
i am led (a)
straight back to you (b)
Explanation:
the a's rhyme and the b's rhyme
