How is the lifespan typically categorized?

Lifespan is typically categorized by stages because this approach highlights the different periods of human development throughout an individual's life. These stages include infancy, childhood, adolescence, adulthood, and old age, each characterized by unique physical, cognitive, and emotional changes. Recognizing these stages allows for a better understanding of the developmental milestones and challenges that individuals face as they progress through life. The categorization by stages also provides a framework for studying human behavior and development in various contexts, such as education, healthcare, and social services, making it an essential concept in psychology, sociology, and related fields.

In contrast, the other options focus on aspects such as environments of learning, specific critical instances in life, or broader social issues, which do not systematically organize the lifespan in a way that reflects the biological and psychological transitions typically experienced as one ages.