**Core Concept**
BCG (Bacillus Calmette-Guérin) vaccine is a live attenuated vaccine used primarily against tuberculosis (TB). The vaccine is administered to protect against severe forms of TB, such as TB meningitis and miliary TB, particularly in high-risk populations like newborns and individuals with compromised immunity.

**Why the Correct Answer is Right**
BCG vaccine is given by the intradermal route, which involves injecting a small amount of the vaccine into the dermal layer of the skin. This route allows for a localized immune response, which is essential for the development of cell-mediated immunity against TB. The intradermal injection also helps to ensure that the vaccine is delivered directly to the lymph nodes, where immune cells can recognize and process the vaccine antigens.

**Why Each Wrong Option is Incorrect**
**Option A:** Oral administration is not suitable for BCG vaccine as it would not provide a localized immune response and would be ineffective in inducing immunity against TB.
**Option B:** Subcutaneous administration is not the preferred route for BCG vaccine as it may not provide adequate immunity and could potentially lead to systemic complications.
**Option C:** Intramuscular administration is not suitable for BCG vaccine as it would not provide a localized immune response and could lead to vaccine antigens being absorbed systemically.

**Clinical Pearl / High-Yield Fact**
BCG vaccine is not effective against pulmonary TB, which is the most common form of TB. However, it can provide protection against severe forms of TB, such as TB meningitis and miliary TB, which are life-threatening conditions.

**Correct Answer:** C. Intradermal