How many pairs of heart are present in earthworm.

Explanation

To answer the question about how many pairs of hearts are present in an earthworm, follow these steps:

### Step-by-Step Solution:

1. **Identify the Circulatory System**:
- Earthworms have a closed circulatory system, which means that blood is contained within blood vessels and does not flow freely in the body cavity.

2. **Understand the Structure of the Heart**:
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