What kind of evidence led scientists studying remains at South Africa's Blombos Cave to suggest ...

What kind of evidence led scientists studying remains at South Africa's Blombos Cave to suggest that they had found proof of symbolic thought dated to more than 70,000 years ago?
 
  A. The tools they found were specialized for different purposes.
  B. Among the bone tools they found were some that were not just sharp but also symmetrical and polished, characteristics that do not add functional value to the tool.
  C. Like Upper Paleolithic cave paintings in Europe, the art in Blombos Cave exhibited graphic representations on its walls.
  D. What looks like rudimentary pedestals were found, which may have been used to exhibit artistic objects.
  E. Among the smaller objects found were earrings and necklaces.