Blood is purified by :

Options

A. Dialysis
B. Electro-osmosis
C. Coagulation
D. Filtration

Answer

To answer the question "Blood is purified by:", we will analyze the different methods mentioned in the video transcript and determine which one is primarily used for blood purification.

### Step-by-Step Solution:

1. **Understanding Dialysis**:
- Dialysis is a process that separates particles based on their size and diffusion through a semi-permeable membrane. In the context of blood purification, it helps remove waste products and excess substances from the blood, making it essential for patients with kidney failure.

2. **Understanding Electroosmosis**:
- Electroosmosis is the movement of liquid through a porous material under the influence of an electric field. While it involves the movement of charged particles, it is not primarily used for blood purification.

3. **Understanding Coagulation**:
- Coagulation refers to the process of aggregating colloidal particles into larger particles that can settle out of a solution. This process is more relevant in blood clotting and not specifically for the purification of blood.

4. **Understanding Filtration**:
- Filtration is a method used to separate solids from liquids or gases using a filter medium. While it can be used in various contexts, it is not the primary method for purifying blood.

5. **Conclusion**:
- Based on the explanations above, the primary method used for blood purification is **dialysis**. Therefore, the answer to the question is that blood is purified by dialysis.

### Final Answer:
Blood is purified by **dialysis**.

---