A 56-year old man presents to his internist with jaundice.The patient is receiving no medication and his only symptomatic complaints is mild fatigue over the past 2 months.Physical examination is remarkable only for the presence of scleral icterus.The patient has no significant past medical history.Analysis of serum chemistry reveals the following: SGOT :0.58 microkat/L (35U/L) SGPT :0.58 microkat/L (35U/L) Total bilirubin:91.7 micron mol/L (7mg/dL) Direct Bilirubin:85.5 micron mol/L (5mg/dL) Alkaline phosphatase:12micron kat/L(720U/L) Which of the following is the next most appropriate diagnostic step?

• A. Ultrasound
• B. Liver biopsy
• C. Review of peripheral blood smear
• D. Endoscopic retrograde cholangiopan-creatography (ERCP)