In Epigeal germination, there is rapid elongation of______

Explanation

**Step-by-Step Solution:**

1. **Understanding Epigeal Germination**: Epigeal germination is a type of seed germination where the cotyledons (seed leaves) are pushed above the soil surface during the germination process.

2. **Identifying the Key Process**: In this type of germination, the main focus is on the elongation of a specific part of the seedling that helps in bringing the cotyledons above the ground.

3. **Recognizing the Part that Elongates**: The part of the seedling that undergoes rapid elongation in epigeal germination is the hypocotyl. The hypocotyl is the stem-like structure that connects the cotyledons to the root.

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