Gibberellins bring about

Options

A. Yellowing of leaves
B. Promotion of rooting
C. Elongation of genetically dwarf plants
D. Dwarfing of genetically tall plants.

Answer

### Step-by-Step Solution:

1. **Understanding Gibberellins**:
- Gibberellins are a group of plant hormones that play a crucial role in various developmental processes in plants.

2. **Growth Promotion**:
- One of the primary functions of gibberellins is to promote the growth of stems and leaves. They stimulate cell elongation and division, leading to increased height and size.

3. **Elongation of Dwarf Plants**:
- Gibberellins are particularly effective in elongating genetically dwarf plants. These plants have a genetic predisposition that limits their growth, but gibberellins can help them overcome this limitation.

4. **Promotion of Flowering**:
- Gibberellins also promote flowering in plants. They can induce flowering even in conditions that are typically not conducive to it, such as short days.

5. **Internode Elongation**:
- Gibberellins cause elongation of internodes, which are the segments of the stem between the nodes. This elongation is essential for the overall height increase of the plant.

6. **Dwarfing of Tall Plants**:
- It is important to note that gibberellins do not cause dwarfing in genetically tall plants; instead, they promote growth.

7. **Conclusion**:
- Based on the functions of gibberellins, the correct answer to the question "Gibberellins bring about" is the "elongation of genetically dwarf plants."