A 67-year-old male presents with complaints of itching, dark urine, and epigastric pain. Physical examination reveals jaundice. Initial laboratory tests show total bilirubin of 6.5 mg/dL, alkaline phosphatase elevated at 3 the upper limit of normal, and mild elevations in serum transaminases. Appropriate management includes which diagnostic test next?
a. Abdominal ultrasonography
b. Computed tomography of the abdomen
c. Magnetic resonance imaging of the abdomen
d. Endoscopic retrograde cholangiography