Which of the following is NOT an assumption of age-stage developmental theorists?

Development is the series of age-related changes that happen over the course of a life span. Several famous psychologists, including Sigmund Freud, Erik Erikson, Jean Piaget, and Lawrence Kohlberg, describe development as a series of stages. A stage is a period in development in which people exhibit typical behavior patterns and establish particular capacities. Age-stage developmental theorists view these age-related stages as discrete and occurring in sequential order. While the last response choice may be true, it is NOT a hallmark of age-stage development theories.