A 15-year-old female wishes to play soccer in school and needs medical clearance. On physical examination, her liver edge is palpable and seems minimally enlarged. Ultrasonography of the liver shows one cyst approximately 3 $\mathrm{cm}$ in diameter. Her menstruation is normal. Results of serologic test results for Echinococus and hepatitis are negative, and liver enzyme values are normal. She has lived her whole life in Salt Lake City, Utah, and has never traveled abroad. Which factor is most important in allowing her to play this sport?

A 15-year-old female wishes to play soccer in school and needs medical clearance. On physical examination, her liver edge is palpable and seems minimally enlarged. Ultrasonography of the liver shows one cyst approximately 3 $\mathrm{cm}$ in diameter. Her menstruation is normal. Results of serologic test results for Echinococus and hepatitis are negative, and liver enzyme values are normal. She has lived her whole life in Salt Lake City, Utah, and has never traveled abroad. Which factor is most important in allowing her to play this sport?

All of the following are requirements for the diagnosis of allergic bronchopulmonary aspergillosis EXCEPT

What is the most appropriate step in the diagnosis of the case described in Question 29?

On examining a full-term newborn, the physician noted mild hepatomegaly. The remainder of the physical findings was normal, including head circumference and retinas. A urine culture grew cytomegalovirus (CMV). Results of head ultrasonography were normal. Subsequent testing disclosed no metabolic disorders. What deficit is most likely to occur in the next year?

A 6-month-old breast-fed infant presents with a 24-hour history of diarrhea but no emesis. On examination, the child is afebrile, has normal vital signs, but has slightly sunken eyes and fontanel. She continues to nurse fairly well. The most appropriate therapy is