When embryo becomes active by imbibing water, it secretes _____hormone.

Explanation

**Step-by-Step Solution:**

1. **Understanding Imbibition**: The process begins when the seed absorbs water, a phenomenon known as imbibition. This is crucial for the seed to become active and initiate germination.

2. **Embryo Activation**: As the seed imbibes water, the embryo within the seed becomes active. This activation is essential for the growth processes to begin.

3. **Hormone Secretion**: Upon activation, the embryo secretes a specific hormone. The hormone secreted during this process is called **gibberellin**.

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