Answer:
This patient's constipatios is due to lack of free water intake.
Step-by-step explanation:
"Free water is the most often forgotten component of tube feeding. While formulas provide some free water, many children require additional fluids in order to have regular stools and stay hydrated."
Reference: FeedingTube Awareness. “Constipation.” Feeding Tube Awareness Foundation, 22 Nov. 2016