The most ancient examples of art, found in caves throughout europe, served to a. tell the story of their tribes. b. playfully decorate the animals they hunted. c. represent sacred gods. d. achieve some purpose that's a mystery.

The correct answer is D.  The purpose of the most ancient examples of cave art (sometimes referred to as “parietal art”), found in caves throughout Europe, remains a mystery.  Most of the drawings depicted animals, but not necessarily the ones that were hunted, based on the type of animal bones deposited in the cave.  Human forms were rare and not as detailed as the animals.  Any religious meanings in the art are purely speculative.

The answer is a : varying the size of objects or subjects, so that some are smaller than others and the illusion of depth is created.hope this : )