Name 2-layered sac surrounding the human heart .

Explanation

### Step-by-Step Solution:

1. **Identify the Structure**: The question asks for the name of the two-layered sac surrounding the human heart.

2. **Name the Sac**: The structure that surrounds the human heart is called the **pericardium**.

3. **Understand the Layers**: The pericardium consists of two main layers:
- **Parietal Pericardium**: This is the outer layer that provides protection and support.
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