A 6-month-old infant is able to lift the head while lying on the stomach, then roll over, and eventually sit with support. This sequence BEST demonstrates which principle of growth and development?

A. Differentiation refers to the progression from simple, global behaviors to more complex, specific skills, such as grasping with fingers instead of the whole hand. While differentiation occurs during development, the sequence described focuses on head-to-toe progression, not skill refinement. B. Proximodistal development describes growth and skill acquisition from the center of the body outward (e.g., control of the trunk before the hands and fingers). The sequence in this example emphasizes head and upper body control first, not central-to-peripheral development. C. Individual differences refer to the variations in the timing and rate at which children reach developmental milestones. While relevant, this principle does not explain the specific head-to-toe progression demonstrated. D. Cephalocaudal development refers to growth and motor control that progresses from head to tail (top to bottom). The infant first gains control of the head and neck, then the upper body, and later the lower body and sitting posture. This head-to-toe pattern of motor development is exemplified by lifting the head, rolling over, and sitting with support.