Jaime and Ryan first noticed that something was wrong with their newborn baby about four months after birth. Their baby seemed to be having difficulty holding her head up. After a series of tests, it was noticed that fatty acids were not being digested by the cells and were accumulating on the child's nerve cells. Which organelle is not properly functioning in the cells of Jaime and Ryan's newborn baby?

Liver

Explanation:

The liver is an organelle in the human body that is responsible for the digestion of fat. Liver produces bile, a digestive juice that helps in the digestion of fats and vitamins. Bile juice is stored in the gall bladder and move into the small intestine for the digestion of fat.

As per the details in the question, a newborn baby is unable to digest fat which is affecting the child's nerve cells. It means the newborn baby's liver is not functioning properly and not making bile juice that can digest the fat properly.

Hence, the correct answer is "Liver".