An attributive noun is a noun that modifies another noun, by giving us more information about the noun. In the given sentence, 'contents' is attributive as it modifies the 'page'.
Options A and B: 'Contents page' is a compound noun that refers to the page in a book with a list of chapters or topics in that book.
'Content', on the other hand, refers to the ideas in a piece of writing.
Both words have different meanings and for the given sentence, 'contents' is relevant.
Hence option B is correct and A is incorrect.
Options C and D: The apostrophe s 's in 'content's' expresses possession or belonging. It is not required in this sentence and it does not form a complete meaning too.
Similarly, the apostrophe in 'contents'' is also not required. Hence options C and D are incorrect.