**Core Concept**
The 'C' Wave in the Jugular Venous Pulse (JVP) reflects the contraction of the right atrium during isovolumetric contraction, preceding the opening of the tricuspid valve. This phenomenon is associated with the increased pressure generated within the right atrium as the ventricles contract.

**Why the Correct Answer is Right**
The 'C' Wave is caused by the contraction of the right atrium, which increases the pressure in the right atrium, thereby compressing the inferior vena cava and causing a positive deflection in the JVP. This wave is seen as a result of the isovolumetric contraction of the right ventricle, which precedes the opening of the tricuspid valve. The exact mechanism behind the 'C' Wave is closely related to the right atrial pressure and the tricuspid valve opening.

**Why Each Wrong Option is Incorrect**
**Option A:** The 'C' Wave is not indicative of the onset of ventricular systole. While it does occur during ventricular contraction, the 'C' Wave specifically represents the right atrial contraction, not the onset of ventricular systole.

**Option B:** The 'C' Wave is not a result of the tricuspid valve closure. In fact, the tricuspid valve is still closed during the 'C' Wave, as it occurs before the valve opens, allowing blood to flow from the right atrium to the right ventricle.

**Option D:** The 'C' Wave is not associated with the opening of the pulmonic valve. The 'C' Wave is a right atrial phenomenon, whereas the opening of the pulmonic valve is related to the right ventricular contraction and the onset of ventricular systole.

**Clinical Pearl / High-Yield Fact**
The 'C' Wave can be remembered by associating it with the contraction of the right atrium during isovolumetric contraction. This is a key concept in understanding the JVP and its various components.

**Correct Answer: C. Right atrial contraction.**