Choose correct one w.r.t. respiratory climactic.

Options

A. Sudden sharp rise in rate of respiration
B. Induced by cytokinins
C. Occur at the time of flowering
D. Decrease in rate of respiration in dormant seeds

Answer

**Step-by-Step Solution:**

1. **Understanding Respiratory Climactic:**
- Respiratory climactic refers to a sudden and sharp increase in the rate of respiration in plants. This phenomenon is significant during specific developmental stages, particularly in fruits.

2. **Role of Ethylene:**
- The primary hormone responsible for inducing respiratory climactic is ethylene. Ethylene is a plant growth regulator (PGR) that is a gaseous hormone. It is produced in large quantities by tissues that are undergoing ripening, especially in fruits.

3. **Effects of Ethylene:**
- Ethylene not only promotes fruit ripening but also enhances the respiration rate. This increase in respiration is what we refer to as respiratory climactic.

4. **Analyzing the Options:**
- **Option 1:** "Sudden sharp rise in rate of respiration" - This is correct as it aligns with the definition of respiratory climactic.
- **Option 2:** "Induced by cytokinins" - This is incorrect because respiratory climactic is induced by ethylene, not cytokinins.
- **Option 3:** "Occurs at the time of flowering" - This is also incorrect. Respiratory climactic occurs during fruit ripening, not flowering.
- **Option 4:** "Decrease in rate of respiration in dormant seeds" - This is incorrect as well. Respiratory climactic is characterized by an increase in respiration, particularly in ripening fruits, not in dormant seeds.

5. **Conclusion:**
- The only correct statement regarding respiratory climactic is that it is characterized by a sudden sharp rise in the rate of respiration.

**Final Answer:**
- The correct option with respect to respiratory climactic is: "Sudden sharp rise in rate of respiration."

---