Final answer:
A developmental stage refers to a period of stability, and a developmental transition refers to a period of change. Stages denote continuous improvement, while transitions involve significant shifts in development.
Step-by-step explanation:
Packer and Cole (2014) make the case that a developmental stage refers to a period of stability, whereas a developmental transition refers to a period of change. Therefore, the correct answer is a) Stability; change. Developmental stages are characterized by a level of consistency where individuals demonstrate continuous improvement like physical growth in height. Meanwhile, developmental transitions, such as adolescence, involve significant shifts in physical, cognitive, and psychosocial realms, marking a distinct departure from previous stages and often entailing rapid changes.