____is a blood protein which is required for clotting of blood.

Explanation

**Step-by-Step Solution:**

1. **Understanding Blood Proteins**: Blood contains various proteins that play essential roles in different bodily functions, including clotting.

2. **Identifying the Protein for Clotting**: Among these proteins, some are specifically involved in the clotting process. The question asks for a protein that is crucial for blood clotting.

3. **Recognizing Fibrinogen**: The specific blood protein required for clotting is called fibrinogen. It is a specialized protein that acts as a clotting factor.

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