A 6-week-old female infant exhibits dry scaly skin and a protruding tongue after having trouble breast-feeding. A diagnosis of congenital hypothyroidism is made. The mother asks the nurse why the child was not diagnosed with this condition at birth. Which of the following would be the nurse’s best response（）
A. "We had the results of the newborn screen, but you did not bring the baby in for the 2-week checkup. "
B. "We could not reach you at home to give you the results of tests taken at birth. "
C. "Your baby had little need for thyroid hormone until she was 1 month old. "
D. "Newborns generally receive enough thyroid hormone from the mother to get by the first few weeks. "