Which of the following forces the plasma to be filtered across the glomerulus?

Options

A. A full urinary bladder
B. Pressure of urine in the glomerulus
C. Pressure of the blood
D. Water retention

Explanation

To determine which force is responsible for filtering plasma across the glomerulus, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Glomerulus Function**: The glomerulus is a network of capillaries located at the beginning of a nephron in the kidney. Its primary function is to filter blood to form urine.

2. **Identify the Forces Involved**: Several forces can influence the filtration process in the glomerulus. These include:
- Hydrostatic pressure (blood pressure)
- Osmotic pressure
- Capsular pressure

3. **Evaluate the Options**:
- **Option A: Full urinary bladder** - This does not directly influence the filtration process in the glomerulus.
- **Option B: Pressure of urine in glomerulus** - This is not a driving force for filtration; it is more about the pressure in the urinary system.
- **Option C: Pressure of blood** - This refers to blood pressure, which is the main driving force for filtration.
- **Option D: Water retention** - This relates to the body's ability to hold onto water but does not directly cause filtration.

4. **Identify the Main Driving Force**: The primary force that drives the filtration of plasma across the glomerulus is the blood pressure. This pressure pushes the plasma from the blood into the Bowman's capsule, initiating the process of urine formation.

5. **Conclusion**: Based on the analysis, the correct answer is **Option C: Pressure of blood**.