Which of the following is an example of a primitive reflex that is present in newborns and typically disappears by 3-4 months of age?

A) Palmer grasp reflex: The palmer grasp reflex is a primitive reflex in which a newborn will grasp an object placed in their hand. While this reflex is present at birth, it typically disappears by 5-6 months of age, not by 3-4 months. The Moro reflex, which is more related to startle and sudden movements, is the correct answer in this case. B) Babinski reflex: The Babinski reflex, in which the toes fan out when the sole of the foot is stroked, is present at birth but typically disappears by 12 months. This reflex is an indicator of neurological development, and its presence beyond the first year could suggest neurological concerns, but it is not the reflex in question here. C) Rooting reflex: The rooting reflex occurs when the newborn turns their head and opens their mouth in response to cheek stimulation, typically to find the nipple for breastfeeding. This reflex is present at birth and usually disappears by 3-4 months, which is similar to the timing mentioned in the question. D) Moro reflex: The Moro reflex is a startle reflex in which the infant spreads their arms and then pulls them back in when they feel a sudden loss of support or a loud noise. This reflex is present at birth and typically disappears by 3-4 months of age. It is considered a classic primitive reflex that fades as the infant's nervous system matures.