**Core Concept**
The rabies virus is a lyssavirus that causes rabies, a fatal viral disease affecting the nervous system. The virus has a unique antigenic structure that elicits an immune response in infected individuals.

**Why the Correct Answer is Right**
The correct antigen responsible for stimulating antibody production in rabies is the **Glycoprotein (G)**. The G protein is a surface glycoprotein that plays a crucial role in the viral replication cycle and is responsible for the attachment of the virus to the host cell receptor. The immune system recognizes the G protein as a foreign antigen and mounts an immune response against it, producing antibodies that help neutralize the virus. This is the primary antigen that elicits a protective immune response against rabies.

**Why Each Wrong Option is Incorrect**
**Option A:** The **Phosphoprotein (P)** is essential for the viral replication process but is not the primary antigen responsible for stimulating antibody production.
**Option B:** The **Matrix protein (M)** is crucial for the assembly and budding of new viral particles but does not stimulate a significant immune response.
**Option C:** The **Nucleoprotein (N)** is a structural protein that encapsulates the viral genome but is not the primary antigen recognized by the immune system.

**Clinical Pearl / High-Yield Fact**
In clinical practice, the rapid diagnosis of rabies can be made by detecting the presence of rabies virus antigens in the cerebrospinal fluid or by performing a direct fluorescent antibody test on brain tissue samples.

**Correct Answer: C. Nucleoprotein (N) is incorrect. The correct answer is the Glycoprotein (G).**