Iron: _______ :: Calcium : Clotting of blood

Explanation

To solve the analogy "Iron: _______ :: Calcium : Clotting of blood," we need to identify the function of iron in the body, just as we know that calcium is involved in blood clotting.

### Step-by-Step Solution:

1. **Identify the function of Calcium**:
- We know that calcium is essential for the clotting of blood. This is a well-established fact in biology.

2. **Identify the function of Iron**:
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