Among `GA_(1), GA_(2) "and" GA_(3)` which one is throughly studied form?

Explanation

**Step-by-Step Solution:**

1. **Understanding Gibberellic Acids**: Gibberellic acids (GAs) are a group of plant hormones that promote growth and influence various developmental processes in plants. There are several forms of gibberellic acid, with more than 100 types identified.

2. **Identifying the Forms**: The question specifically mentions three forms: GA₁, GA₂, and GA₃. Each of these forms has different characteristics and levels of activity in promoting plant growth.

3. **Historical Context**: Among these forms, GA₃ is the most notable because it was the first gibberellin to be discovered. It was isolated from a fungus known as Gibberella fujikuroi, which is a pathogen that affects rice plants.

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