**Core Concept**
The patient in question has been exposed to Hepatitis C virus (HCV) and has developed antibodies against it, indicating a chronic infection. However, the absence of liver enzyme elevation (normal AST/ALT) and symptoms or stigmata of liver disease suggests a possible early stage of the disease or a mild infection.

**Why the Correct Answer is Right**
The correct approach would be to perform an HCV RNA test to determine if the patient is actively infected with the virus. This test can differentiate between acute and chronic infections, as well as detect the presence of the virus in the blood. The presence of HCV RNA would indicate an active infection, whereas the absence would suggest a resolved or cleared infection. This approach is crucial in determining the next steps in management, such as antiviral therapy or close monitoring.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not address the need to determine the presence of the virus in the blood. A liver biopsy may be considered later in the management of chronic HCV, but it is not the initial step.

**Option B:** This option is incorrect as it does not provide a clear plan for managing the patient's HCV infection. Antiviral therapy is considered in patients with chronic HCV, but it is not indicated in this scenario without further testing.

**Option C:** This option is incorrect as it does not address the need to determine the presence of the virus in the blood. A hepatitis A vaccine is not indicated in this scenario, as the patient is already exposed to HCV.

**Option D:** This option is incorrect as it does not provide a clear plan for managing the patient's HCV infection. A liver ultrasound may be considered later in the management of chronic HCV, but it is not the initial step.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that HCV RNA testing is the most appropriate initial step in diagnosing HCV infection, as it can differentiate between acute and chronic infections.

**Correct Answer:** C.