Phytohormone commonly called stress hormone is
(a) Auxin
(b) Abscisic acid
(c) Gibberellin
(d) Cytokinins

Options

A. Auxin
B. Abscisic acid
C. Gibberellin
D. Cytokinins

Answer

To answer the question about which phytohormone is commonly referred to as the "stress hormone," follow these steps:

### Step 1: Understand the Question
The question asks for the phytohormone that is commonly known as the stress hormone.

### Step 2: Analyze the Options
The options provided are:
(a) Auxin
(b) Abscisic acid
(c) Gibberellin
(d) Cytokinins

### Step 3: Recall the Functions of Each Hormone
- **Auxin**: Primarily involved in cell elongation and growth, particularly in response to light and gravity.
- **Abscisic Acid (ABA)**: Known for its role in stress responses, particularly in drought conditions. It promotes seed dormancy and helps plants cope with environmental stress.
- **Gibberellin**: Promotes stem elongation, seed germination, and flowering.
- **Cytokinins**: Promote cell division and growth, and delay senescence.

### Step 4: Identify the Stress Hormone
From the analysis, **Abscisic Acid (ABA)** is recognized for its role in helping plants manage stress, particularly during unfavorable environmental conditions. It is often referred to as the stress hormone.

### Step 5: Select the Correct Answer
Based on the above analysis, the correct answer is (b) Abscisic acid.

### Final Answer
The phytohormone commonly called the stress hormone is **(b) Abscisic acid**.

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