The elongation of genetically dwarf plants is brought about by the application of :

Options

A. Cytokinins
B. Gibberellins
C. X - Rays
D. Vitamin 'C'

Answer

To solve the question regarding the elongation of genetically dwarf plants, we will analyze the options provided and determine which one is correct.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks which substance can promote the elongation of genetically dwarf plants. Dwarf plants are characterized by their short stature due to genetic factors.

2. **Analyzing the Options**:
- **Option 1: Cytokinins**: These are plant hormones that promote cell division and growth. While they do stimulate growth, they are more associated with shoot and root development rather than elongation specifically.
- **Option 2: Gibberellins**: These are plant growth regulators known for promoting stem elongation and breaking dormancy in seeds. They are particularly effective in overcoming the dwarfism caused by genetic factors.
- **Option 3: X-rays**: This option is not relevant as X-rays are a form of radiation and do not function as a growth regulator.
- **Option 4: Vitamin C**: While important for overall plant health and metabolism, it does not directly promote elongation in plants.

3. **Conclusion**: After evaluating all the options, it is clear that gibberellins (Option 2) are the hormones responsible for promoting the elongation of genetically dwarf plants.

### Final Answer:
The elongation of genetically dwarf plants is brought about by the application of **Gibberellins**.