During ripening of the fruits, rate of respiration is increased under the influence of hormone. It is called Climacteric respiration and The hormone is -

Options

A. ABA
B. Auxin
C. `C_2 H_4`
D. `GA`

Answer

**Step-by-Step Solution:**

1. **Understanding Climacteric Respiration:**
- Climacteric respiration refers to a significant increase in the rate of respiration that occurs during the ripening of certain fruits. This physiological response indicates that the fruit is nearing full maturity and that senescence (aging) is beginning.

2. **Identifying the Hormone:**
- The hormone responsible for triggering climacteric respiration is ethylene. Ethylene is a gaseous plant hormone that plays a crucial role in the ripening process of fruits.

3. **Chemical Composition of Ethylene:**
- Ethylene is represented by the chemical formula C2H4. It is classified as a plant growth regulator (PGR) and is known for its effectiveness in promoting fruit ripening.

4. **Conclusion:**
- Therefore, during the ripening of fruits, the increased rate of respiration, known as climacteric respiration, is influenced by the hormone ethylene.

**Final Answer:**
The hormone responsible for climacteric respiration during fruit ripening is ethylene (C2H4).

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