Answer : 2. "transpiration"
Explanation :

1. Plants release water into the air through a process called transpiration.

2. Transpiration is a natural process, by which plants expel water from their bodies in the form of vapor.

3. The process of transpiration takes place through small holes in the leaves, which are called stomata.

3. Transpiration is essential for plants, as it helps keep plants cool and transport nutrients from the roots to the leaves needed to make food.