Final answer:
The probable cause of feeding difficulties in a neonate with Down syndrome is the tongue thrust reflex, which can make bottle or breast feeding challenging for the infant.
Step-by-step explanation:
The mother of a neonate with Down syndrome is concerned about feeding difficulties her baby is experiencing. Among the options presented, the probable cause of these feeding difficulties is C. Tongue thrust. Newborns with Down syndrome often exhibit reduced muscle tone and motor skills, which can include a tongue thrust reflex, where the tongue pushes against any object placed in the mouth, including a nipple or bottle. This can make feeding challenging. Although a receding jaw may also be present in Down syndrome patients, tongue thrust is more directly related to feeding issues. Issues such as brain damage and nasal congestion could also contribute to feeding difficulties but are not as strongly associated with Down syndrome as the tongue thrust reflex.