How could Robert Hall's interpretations about the symbolic meanings of Hopewell effigy pipes be ...

How could Robert Hall's interpretations about the symbolic meanings of Hopewell effigy pipes be tested?
 
  a. They could be tested directly simply by examining ethnographic data relating to the symbolic meaning of historic peace pipes.
  b. They could be tested indirectly by assessing the archaeological record of the Hopewell Interaction Sphere, and determining whether the social and political ramifications predicted by Hall's hypothesis are archaeologically visible.
  c. If abundant evidence of conflict is present in Hopewell sites along with abundant effigy pipes, Hall's interpretation would be supported.
  d. They could not be tested; this is the major problem with cognitive archaeological approaches.
  e. Linking them to phenomena that are more archaeologically accessible is not an option but technology is emerging that will enable the hypothetical interpretations to be tested.