The true statement about every public domain work is:
It is not protected by copyright or Creative Commons licenses.
Public domain works are free for anyone to use without permission or the need to pay royalties, as they are not protected by copyright or Creative Commons licenses. The other statements may be true in some cases but are not universally applicable to all public domain works. For instance, a public domain work does not have to be 100 years old or considered of great merit, and it can be a type of work other than art, literature, or music.