According to Piaget, there are three significant equilibration points, each ushering in a new stage of development. When do they occur?
a. 18 months, ages 5 to 7, and late childhood
b. 18 months, late childhood, and adolescence
c. 6 months, 18 months, 24 months
d. infancy, toddlerhood, preschool
e. 18 months, ages 5 to 7, adolescence