Colouring agent fo plasma is `:-`

Options

A. Billiverdin
B. Stercobillinogen
C. Urobillinogen
D. Urochrome

Answer

### Step-by-Step Solution:

1. **Understanding Plasma Composition**: Plasma is the liquid component of blood and is primarily composed of water (about 90-92%) and dissolved substances (about 8-10% solid particles).

2. **Identifying the Coloring Agent**: The question asks for the coloring agent of plasma. While plasma itself is mostly transparent, it contains various substances that can impart color.

3. **Role of Hemoglobin**: Hemoglobin, the protein in red blood cells, is responsible for transporting oxygen and carbon dioxide. When hemoglobin breaks down, it produces several byproducts.

4. **Byproducts of Hemoglobin Breakdown**: The breakdown of hemoglobin leads to the formation of several pigments, including biliverdin, stercobilinogen, and urobilinogen. These pigments are associated with the metabolism of hemoglobin.

5. **Identifying Urochrome**: Among the byproducts mentioned, urochrome is specifically known as the pigment that gives urine its yellow color. It is a product of the breakdown of hemoglobin and is present in plasma.

6. **Conclusion**: Therefore, the coloring agent of plasma is **urochrome**.

### Final Answer:
The coloring agent of plasma is **urochrome**.

---