A psychologist is counseling a client who struggles with being overly rigid and controlling. The psychologist theorizes that the client's issues stem from an unresolved conflict during a specific, early period of their life, and that this unresolved conflict has prevented them from fully progressing to later phases of personal growth. Which of the following statements best describes the psychologist's underlying assumption about development?

A psychologist who views development as a process occurring in a series of distinct, sequential phases is analyzing an adult client who is excessively rigid, orderly, and obsessed with control. Which of the following conclusions best aligns with the psychologist's theoretical perspective?