Plant Hormones

Step 1: Assertion analysis.
Abscisic acid (ABA) is a plant hormone that plays a crucial role in regulating plant responses to stress, especially during drought conditions. One of its primary functions is to promote stomatal closure, which helps reduce water loss through transpiration, thereby conserving water.
Step 2: Reason analysis.
The reason states that abscisic acid helps the plant conserve water during stress, which is also true. ABA promotes stomatal closure, thus reducing transpiration and water loss during drought, helping the plant survive stressful conditions.
Step 3: Conclusion.
Since both the assertion (A) and the reason (R) are true, and the reason (R) directly explains the assertion (A), the correct answer is (C). Final Answer: (C) Both (A) and (R) are true and (R) is the correct explanation of (A).