Final answer:
Option 2: Encourage the mother to hold the infant when the infant cries, is the best measure to promote parent-infant bonding, utilizing the infant's developed sense of touch and preferences for the mother's voice and scent.
Step-by-step explanation:
The optimal measure to promote parent-infant bonding postpartum, according to the sensory development and needs of neonates, would be option 2: Encourage the mother to hold the infant when the infant cries. The sense of touch is well-developed at birth, and neonates respond positively to physical contact such as soft stroking, cuddling, and being held. Since newborns have a preference for their mother's voice and scent, encouraging the mother to soothe her crying infant by holding them can enhance bonding, as well as provide sensory comfort to the baby. This aligns with the understanding that infants have a basic need for close physical contact, as shown through innate reflexes like the Moro and grasping reflexes. It also takes into consideration the soothing effect that the mother's voice and scent can have on the infant.