D. orals through memorization, but the better ones require thought. Maybe the Chinese Emperor would have been better served by somebody who thought than by somebody who remembered, and, perhaps, that's why there is no more a Chinese Emperor. This is simply not true. Animals can only perceive and react. An animal can be trained to react in the same manner given the same stimulus, but it ain't memorization.
Memorization is an atrophied part of our education, once a key part of rhetoric studies.
It took the great memory skills of Matteo Ricci to work his way up to advisor to the Chinese Emperor. I'd like to see a pigeon do that.