Agglutinin are present in `:-`

Options

A. RBC
B. WBC
C. Serum
D. Spleen

Answer

**Step-by-Step Solution:**

1. **Understanding Agglutinins**: Agglutinins are substances that cause agglutination, which is the clumping of cells. In the context of blood, they are antibodies that react with specific antigens present on the surface of red blood cells (RBCs).

2. **Location of Agglutinins**: Agglutinins are primarily found in the plasma or serum of the blood. Plasma is the liquid component of blood that remains after the blood cells have been removed, while serum is the fluid that remains after coagulation.

3. **Role of Agglutinins**: These antibodies bind to antigens on the surface of RBCs. For example, blood groups are determined by the presence or absence of specific antigens (A or B) on the RBCs. Agglutinins will react with these antigens to form clumps.

4. **Conclusion**: Therefore, agglutinins are present in the serum of the blood.

**Final Answer**: Agglutinins are present in the serum.

---