Read the following functions performed by plant hormones:
a) regulates dormancy
b) inhibits metabolism
c) stimulates stomatal closure
d) inhibits seed germination
Which of these is involved in ALL of the above functions?

Options

A. Indole acetic acid
B. Naphthalene acetic acid
C. Indole butyric acid
D. Abscisic acid

Answer

To solve the question regarding which plant hormone is involved in all the listed functions (regulates dormancy, inhibits metabolism, stimulates stomatal closure, and inhibits seed germination), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Functions**:
- The functions mentioned are:
a) Regulates dormancy
b) Inhibits metabolism
c) Stimulates stomatal closure
d) Inhibits seed germination

2. **Understand Plant Hormones**:
- Plant hormones (phytohormones) can be classified into several types, including auxins, gibberellins, cytokinins, ethylene, and abscisic acid (ABA).

3. **Analyze Each Function**:
- **Regulates Dormancy**: This is primarily associated with abscisic acid (ABA), which helps maintain seed dormancy.
- **Inhibits Metabolism**: ABA is known to inhibit metabolic processes during stressful conditions.
- **Stimulates Stomatal Closure**: ABA plays a crucial role in closing stomata to reduce water loss during drought conditions.
- **Inhibits Seed Germination**: ABA prevents premature germination of seeds, maintaining dormancy until conditions are favorable.

4. **Identify the Common Hormone**:
- After analyzing the functions, it is clear that abscisic acid (ABA) is involved in all four functions listed. It is often referred to as the stress hormone due to its role in responses to environmental stress.

5. **Conclusion**:
- Therefore, the hormone involved in all of the above functions is **abscisic acid (ABA)**.

### Answer:
The correct answer is **abscisic acid (ABA)**.

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