Which of the following is an example of a key element of Jean Piaget’s theory of cognitive development? A. Stephani’s reading progressed the same from seventh grade to eighth grade as it did from first grade to second grade.

B. Catherine finally realized her grandfather is her father’s father.

C. Erin excelled at math despite the fact that she did not have good math teachers.

D. Courtney’s ability to read was equally influenced by all the books in her home and her age.

E. Spencer’s vocabulary increased by the same number of words every ten years throughout his life.