12. You definitely cannot use any piece of art... A. that is public domain
B. with a copyright symbol
C. that is over 100 years old
D. without any indication of who made it

Photography has changed its subject matter quite a lot over the past few years. in the 1800's, it was considered normal for families to have  post mortem photos of their loved ones, and now that would be completely unacceptable. i think that photographers have always pushed boundaries and have been eager to capture everything, it is just society that changes their boundaries.