Haematocrit is ratio of `:-`

Options

A. WBC to plasma
B. Platelet to plasma
C. Blood cells to plasma
D. RBC to plasma

Answer

### Step-by-Step Solution:

1. **Understanding Haematocrit**:
- Haematocrit is a term used to describe the proportion of blood that is made up of red blood cells (RBCs). It is also known as packed cell volume (PCV) or erythrocyte volume fraction.

2. **Defining the Ratio**:
- The haematocrit value is essentially a volume percentage of RBCs in the total blood volume. This means it measures how much of the blood is composed of red blood cells compared to the liquid component (plasma).

3. **Analyzing the Options**:
- The question provides several options:
- WBC to plasma
- Platelet to plasma
- Blood cell to plasma
- RBC to plasma
- We need to identify which of these options correctly describes haematocrit.

4. **Evaluating Each Option**:
- **WBC to plasma**: This is incorrect as it refers to white blood cells, not red blood cells.
- **Platelet to plasma**: This is also incorrect since it involves platelets, which are not the focus of haematocrit.
- **Blood cell to plasma**: This option is too broad as it includes all blood cells, not specifically RBCs.
- **RBC to plasma**: This option is correct as haematocrit specifically measures the volume percentage of red blood cells in the blood.

5. **Conclusion**:
- The correct answer is **RBC to plasma**. Haematocrit is the ratio of red blood cells to plasma in the blood.