A parent tells the nurse, "My 9-month-old baby no longer has the same strong grasp that was present at birth and no longer acts startled by loud noises." How should the nurse explain these changes in behavior?
Correct Answer: D
Rationale: The correct answer is D: "These responses are replaced by voluntary activity at about five months of age." The grasp reflex and startle reflex (Moro reflex) are normal in newborns but typically disappear as the infant's nervous system matures and voluntary control develops. Choice A is incorrect because checking the responses before deciding a course of action does not address the developmental milestone related to the reflexes. Choice B is incorrect as it jumps to a conclusion of developmental delay without considering the normal developmental process. Choice C is incorrect as additional sensory stimulation is not necessary for the return of these reflexes, as they are expected to naturally diminish as part of normal development.