Which reflex is expected in infants when they are startled?

The Moro reflex, also known as the startle reflex, is a protective and reflexive response seen in infants when they experience a sudden change in their environment, such as a loud noise or a feeling of falling. In this reflex, the infant will typically extend their arms and legs away from their body and then quickly bring them back in, often accompanied by a crying response. This reflex is an important indicator of neurological development and usually appears at around 28 weeks of gestation, peaking at 2 to 4 months of age and gradually disappearing by the time the child is about 6 months old.

The rooting reflex, on the other hand, involves an infant turning their head toward a stimulus that touches their cheek, aiding in breastfeeding. The grasp reflex is demonstrated when an infant automatically grips an object placed in their palm. Lastly, the tonic neck reflex, also known as the "fencing reflex," occurs when an infant turns their head to one side and extends the arm and leg on that side while flexing the limbs on the opposite side.

While all of these reflexes are significant in the assessment of infant development, the Moro reflex specifically addresses the response to startling stimuli, making it the correct answer for the scenario described.