A 30-year-old man comes to your office with complaints of fatigue, anorexia, nausea, and vomiting. He does not have fever. His urine is dark. On physical examination, his liver is slightly enlarged and minimally tender. He does not have edema or spider angiomata. Laboratory tests show the following: negative HBsAg, negative IgM anti-HAV, positive IgM anti-HBc, and negative anti-HCV. The most likely diagnosis is
a. Acute hepatitis A
b. Acute hepatitis B
c. Acute hepatitis A and B
d. Chronic hepatitis B
e. Acute hepatitis C
Ans: b. Acute hepatitis B
Explanation: acute HBV infection signaled by the positive IgM anti-HBC