I'll give you a question, please answer with step-by-step reasoning process. Two bookends were on the shelf. They supported a line of what?\nOptions:\n- librarian\n- pair\n- school library\n- library book\n- bookshelf

User
Library books are kept in a shelf. Bookends are used to prevent books in a shelf from falling. Library books need bookends to be supported.
The answer: library book.
Assistant