A. Firsthand accounts.
Libraries is exactly what you think it is: books and resources. Newspapers can be stored and even given if requested. Magazines and non-fiction books is what a library is all about: reading. Firsthand accounts is more the person experienced the events themselves and is giving their input. While this could happen, it’s not very likely. You wouldn’t ask the librarian what happened in World War 2 because they weren’t there. Second hand account is more of them telling you based on events they know but they weren’t there. That is more common than first hand in libraries.