**Core Concept**
The patient is a young male with a positive HBsAg (hepatitis B surface antigen) test result and a negative HBeAg (hepatitis B e-antigen) test result. This suggests that the patient is a carrier of hepatitis B virus (HBV) but is not actively replicating the virus. The presence of normal liver enzymes indicates that the patient is not experiencing active liver inflammation.

**Why the Correct Answer is Right**
The next step in managing this patient is to perform a liver ultrasound to assess for liver fibrosis and to rule out any complications such as hepatocellular carcinoma (HCC) or cirrhosis. This is because chronic HBV infection can lead to liver fibrosis and cirrhosis, even in the absence of active liver inflammation. The ultrasound will also provide information about the size and structure of the liver, which can be useful in assessing the patient's risk of developing HCC.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not address the patient's need for liver fibrosis assessment and HCC screening. While antiviral therapy may be necessary for some patients with chronic HBV infection, it is not the next step in management for this patient.

**Option B:** This option is incorrect because it does not address the patient's need for liver fibrosis assessment and HCC screening. While liver biopsies are useful for diagnosing liver disease, they are not the next step in management for this patient.

**Option C:** This option is incorrect because it does not address the patient's need for liver fibrosis assessment and HCC screening. While antiviral therapy may be necessary for some patients with chronic HBV infection, it is not the next step in management for this patient.

**Clinical Pearl / High-Yield Fact**
Chronic HBV infection can lead to liver fibrosis and cirrhosis, even in the absence of active liver inflammation. Regular liver ultrasounds and HCC screening are essential for patients with chronic HBV infection to prevent and detect complications early.

**Correct Answer:** C. Liver ultrasound