A 14-year-old girl sitting in the lodge is complaining of severe abdominal and flank pain. She tells you that her symptoms started a couple of days ago but have worsened over the last few hours. She has chills and thinks she might have a fever. Based on her complaints, you are concerned that she may have:

a. cholecystitis.
b. pyelonephritis.
c. hepatitis.
d. nephrolithiasis.

Answer: b