Given below are group of terms. In each group the first pair indicates the relationship between the two terms. Rewrite and complete the second pair on a similar basis.
Example : Oxygen : Inspiration :: Carbon dioxide : Expiration
Foetus: Amnion :: Heart : ____.

Explanation

To solve the question, we need to identify the relationship between the first pair of terms and then apply that same relationship to complete the second pair.

### Step-by-Step Solution:

1. **Identify the Relationship in the First Pair:**
- The first pair is "Foetus : Amnion".
- Here, the relationship is that the amnion is a protective membrane that surrounds and covers the foetus.

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