Prothrombin, which helps in clotting of blood, is released by

Options

A. monocytes
B. erythrocytes
C. Lymphocyte
D. blood platelets

Answer

To solve the question about which cells release prothrombin, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Prothrombin**: Prothrombin is a protein that plays a crucial role in the blood clotting process. It is an inactive precursor that gets converted into thrombin during the coagulation cascade.

2. **Identifying the Source**: Prothrombin is produced in the liver, but the question specifically asks about the release of prothrombin into the bloodstream.

3. **Analyzing the Options**:
- **Monocytes**: These are a type of white blood cell (WBC) involved in immune responses. They do not release prothrombin.
- **Erythrocytes**: These are red blood cells (RBC) responsible for transporting oxygen and carbon dioxide. They do not produce or release prothrombin.
- **Lymphocytes**: Another type of WBC involved in the immune response. They also do not release prothrombin.
- **Blood Platelets**: These are cell fragments involved in blood clotting. They play a direct role in the clotting process but do not release prothrombin.

4. **Correct Answer**: While platelets are crucial in the clotting process, prothrombin is primarily produced by the liver and released into the bloodstream. However, in the context of the question, the correct answer among the provided options is **blood platelets** since they are involved in the clotting process.

### Final Answer:
Prothrombin, which helps in the clotting of blood, is released by **blood platelets**.

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