The true statement about every public domain work is:
It is not protected by copyright or Creative Commons licenses.
Public domain works are those whose copyrights have expired, been forfeited, or are inapplicable, meaning they are free for anyone to use without seeking permission. The other statements about public domain works may not necessarily be true for all of them. For example, not every public domain work is 100 years old or considered to have great artistic or scientific merit.