A 42-year-old woman comes to the physician for a routine examination. She says that she has felt well except for occasional episodes of constipation, abdominal discomfort, and mild fatigue. She was treated for a renal calculus 10 years ago and was told she had a "lazy gallbladder." Her pulse is 82/min, and blood pressure is 150/80 mm Hg. Her Ca2+ is high, phosphorus is low, and ALP is high. There is a well-defined nodule in what location?

A) Pancreas
B) Kidney
C) Liver
D) Parathyroid gland