Abscisic acid controls
(a) Cell elongation and cell wall formation
(b) Shoot elongation
(c) Leaf fall and dormancy
(d) Cell division

Options

A. Cell elongation and cell wall formation
B. Shoot elongation
C. Leaf fall and dormancy
D. Cell division

Answer

To determine the correct answer to the question regarding the role of abscisic acid (ABA), we can analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Abscisic Acid (ABA)**:
- Abscisic acid is a plant hormone that plays a crucial role in plant responses to stress, particularly environmental stress such as drought and salinity.
- It is often referred to as a stress hormone because it helps plants cope with adverse conditions.

2. **Analyzing Each Option**:
- **(a) Cell elongation and cell wall formation**:
- This function is primarily associated with other hormones, such as auxins. Therefore, this option is incorrect.

- **(b) Shoot elongation**:
- Shoot elongation is mainly regulated by gibberellins, not abscisic acid. Thus, this option is also incorrect.

- **(c) Leaf fall and dormancy**:
- Abscisic acid is known to promote leaf abscission (leaf fall) and seed dormancy. This is a key function of ABA, making this option correct.

- **(d) Cell division**:
- Cell division is generally influenced by cytokinins, not abscisic acid. Therefore, this option is incorrect.

3. **Conclusion**:
- Based on the analysis, the correct answer is **(c) Leaf fall and dormancy**.

### Final Answer:
**(c) Leaf fall and dormancy**