I would say the correct answer is C. She filled her living room with dozens of tulips. A is incorrect because there should be a hyphen between five and dozen: five-dozen eggs because it is a compound adjective. B is incorrect because the word thousands should be singular: seven thousand people/thousands of people (without seven). D is incorrect because the word hundred should be plural: hundreds of quilt. This leaves us with C as the correct answer.
Answer: The title of the book is "Penny in the Sand" when the writer said the phrase: "Bury it deep in the sand" He was making a reference to the title of the book.