If William is a preoperational-stage thinker and Mary is a concrete-operational thinker,which term would a Piagetian use to characterize the difference between William and Mary's intellectual skills?

A) primary
B) secondary
C) quantitative
D) qualitative

Piaget would use the term "qualitative" to characterize the difference between William (preoperational) and Mary (concrete-operational). This is because they differ in the way they think and process information, with William relying on symbolic thinking and Mary being able to think logically and concretely. This is a qualitative difference in cognitive skills, rather than just a quantitative difference in the amount of knowledge or information they possess.