The type of study that Dr. Chang is describing, in which he followed one group of individuals from infancy into early adulthood, is called a(n)

dropdown

study.

A. simple reflexes: In Piaget’s sensorimotor substages, the first substage (0–1 month) is characterized by simple reflexes (e.g., rooting, sucking), so this is the correct label.
B. gross motor skills: Gross motor skills refer to large-muscle actions like crawling or walking, not the category name for newborn reflexes.
C. fine motor skills: Fine motor skills involve controlled hand/finger movements and are not the term used for newborn reflexive behaviors like rooting and sucking.
D. habits: “Habits” or primary circular reactions appear in later substages (e.g., repeating actions) rather than the initial reflexive substage.

A. rooting: Rooting causes head-turning toward cheek stimulation to find a nipple; it does not produce full-body startle responses.
B. Moro: The Moro (startle) reflex produces arm abduction/extension, head throwing back, and sometimes crying in response to a sudden stimulus — this matches the description.
C. sucking: Sucking is an oral reflex triggered by placing something in the mouth; it doesn’t cause arching and arm flinging.
D. grasping: The grasp (palmar) reflex causes fingers to close around an object, not the described startle posture.