**Core Concept**
The Hepatitis B vaccine is a crucial preventive measure for adults at risk of Hepatitis B virus (HBV) infection. The vaccine's administration schedule is essential to ensure optimal immune response and prevent vaccine-related adverse effects.

**Why the Correct Answer is Right**
The correct answer is the standard dosage and administration schedule recommended by the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO). The adult Hepatitis B vaccine series consists of 2 doses of 1-mL injections administered intramuscularly, 1-2 months apart. This delayed booster shot allows for the optimal production of antibodies against the HBV surface antigen.

**Why Each Wrong Option is Incorrect**
**Option A:** This option may be incorrect if it suggests a different dosage or administration schedule than the standard 2-dose series.

**Option B:** This option may be incorrect if it implies a different vaccination interval, such as a shorter or longer time between doses.

**Option C:** This option may be incorrect if it suggests a different type of vaccine, such as a monovalent or combination vaccine, rather than the standard recombinant Hepatitis B vaccine.

**Clinical Pearl / High-Yield Fact**
The Hepatitis B vaccine is highly effective in preventing HBV infection and its complications, including liver cirrhosis and hepatocellular carcinoma. However, it is essential to complete the full 2-dose series to ensure optimal protection against HBV.

**Correct Answer:** C. 2 doses of 1-mL injections administered intramuscularly, 1-2 months apart.