<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 60-year-old rock musician presents to the office because he has been feeling increasingly tired for the past 6 months. He has a history of intravenous drug use and alcohol abuse. He states that he feels quite tired, but he otherwise has no complaints. Physical examination is noncontributory. His laboratory values are normal other than moderately elevated liver enzymes. Which of the following additional tests should you order first?? A: Hepatitis A virus-specific IgM antibodies, B: Hepatitis B surface antigen, C: Hepatitis C virus RNA, D: Hepatitis D virus-specific IgG antibody, E: Hepatitis E virus-specific IgM antibodies,  <response>: This question is asking about the appropriate initial diagnostic test to order for a 60-year-old patient with a history of IV drug use and alcohol abuse who presents with fatigue and elevated liver enzymes. The key facts are the patients age, history of IV drug use and alcohol abuse, fatigue, elevated liver enzymes, and lack of other symptoms or abnormal physical exam findings. This presentation is most concerning for chronic hepatitis C infection given the IV drug use history. Hepatitis C is the most common cause of chronic viral hepatitis in the US. The initial diagnostic test would be to check a hepatitis C viral load by PCR. Hepatitis A and E would cause acute infection, not chronic, and are less likely. Hepatitis B surface antigen would detect a chronic hepatitis B infection but is less likely than hepatitis C given the specific risk factor of IV drug use. Hepatitis D can only occur as a coinfection with hepatitis B. Therefore, the best initial test is a hepatitis C viral load.C: Hepatitis C virus RNA 