Agglutinogens are found in

Options

A. blood plasma
B. RBC surface
C. WBC
D. platelets

Explanation

### Step-by-Step Solution:

1. **Understanding Agglutinogens**: Agglutinogens are specific types of antigens found on the surface of red blood cells (RBCs). They play a crucial role in determining an individual's blood group.

2. **Role in Blood Grouping**: The presence of different agglutinogens (such as A and B) on the RBCs helps classify blood into different groups (A, B, AB, and O). Each blood group has a specific combination of agglutinogens.

3. **Interaction with Agglutinins**: Agglutinogens interact with agglutinins (antibodies) present in the plasma. For example, A-agglutinogens will bind to A-agglutinins, leading to agglutination if incompatible blood types are mixed.

4. **Location of Agglutinogens**: The agglutinogens are located on the surface of red blood cells. This is where they exert their function in blood typing and immune response.

5. **Conclusion**: Therefore, the correct answer to the question "Agglutinogens are found in" is that they are found in red blood cells (RBCs).

### Final Answer:
Agglutinogens are found in red blood cells (RBCs).

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