During a well-child visit, a nurse notes that a toddler has recently started speaking in short sentences, but gross motor skills such as running have shown little change. Which principle does this BEST illustrate?

A. Directional trends describe the general patterns of growth, such as cephalocaudal (head-to-toe) or proximodistal (center-to-periphery) development. The scenario focuses on differences in the rate of skill acquisition, not the direction of development. B. Developmental pace refers to the rate at which different skills or abilities emerge, which can vary among domains. In this scenario, the toddler’s language skills are advancing rapidly, while gross motor skills like running show little change, illustrating that different areas of development progress at different rates. C. Sensitive periods refer to specific windows of time during which a child is particularly responsive to certain types of learning or stimuli, such as language acquisition. The scenario does not specify a critical timing for development, but rather differences in progression across skills, so sensitive periods are not the primary principle illustrated. D. Sequential trends refer to the orderly and predictable progression of developmental milestones, such as crawling before walking. While the toddler is developing language, the scenario emphasizes rate differences, not the order in which skills emerge.