Traces of Art Have Been Found in Upper Paleolithic Sites

Traces of art have been found in Upper Paleolithic sites. Most paintings were only of animals. This is believed to be because

A) they may have thought that pictures of humans could cause injury or death.
B) they may have thought theses pictures would improve their luck at hunting.
C) they may have thought the pictures would increase the supply of animals.
D) all of the above.