Why do many archaeologists feel that oral traditions are not as reliable a source of information as archaeological data? a. oral traditions can change over time; the older the events described, the more likely that elements were dropped or added. b. oral traditions can be selective in what they remember, altering the nature or sequence of events over time to suit particular political needs. c. oral traditions often encode cultural and religious knowledge that is not rooted in the material world, and that therefore cannot be scientifically evaluated. d. all of the above?