A Nine-Month-Old Infant Is Hospitalized with Vomiting and Diarrhea

A nine-month-old infant is hospitalized with vomiting and diarrhea. The mother questions why her child needed hospitalization since her school-age nephew had the same symptoms and was treated at home. The nurse would explain that an infant is more at risk for dehydration than a school-age child because:

A) Infants have a lower proportion of their body weight as water.
B) The percentage of extra-cellular fluid is higher in the infant than the school-age child.
C) School-age children have a larger body surface area.
D) The school-age child's kidneys are more mature and better able to conserve water.
E) The metabolic rate of the school-age child is higher.