Why does the author mention a "a block of decorated ochre and sets of shell beads" A. To help make the point that archaeologists regard artistic creations as the highest kind of human achievement B. To illustrate how the discovery of certain objects makes the discovery of certain other objects more likely C. To give some of the evidence that has changed archaeologists' thinking about human intellectual development D. To help explain why archaeologists have been slow to recognize the importance of certain evidence available to them