Which of the following techniques can be used to introduce foreign DNA into cell ?

Options

A. Using disarmed pathogen
B. Microinjection
C. Gene gun
D. All of these

Answer

To answer the question "Which of the following techniques can be used to introduce foreign DNA into a cell?" we will analyze each option provided and determine their validity.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks which techniques can be used to introduce foreign DNA into a cell. This is a fundamental aspect of genetic engineering.

2. **Analyzing Option A: Using Disarmed Pathogen**:
- Disarmed pathogens are genetically modified viruses or bacteria that have lost their ability to cause disease. They can be used as vectors to deliver foreign DNA into host cells without causing harm.
- **Conclusion**: This technique can be used to introduce foreign DNA.

3. **Analyzing Option B: Microinjection**:
- Microinjection involves using a fine glass pipette to inject foreign DNA directly into the nucleus of a cell. This method is commonly used in transgenic research.
- **Conclusion**: This technique can also be used to introduce foreign DNA.

4. **Analyzing Option C: Gene Gun**:
- A gene gun is a device that shoots tiny particles coated with DNA into cells at high velocity. This method is effective for introducing DNA into plant cells and some animal cells.
- **Conclusion**: This technique can be used to introduce foreign DNA as well.

5. **Analyzing Option D: All of These**:
- Since all the previous options (A, B, and C) are valid techniques for introducing foreign DNA into cells, option D, which states "All of these," is correct.

6. **Final Answer**: Therefore, the correct answer is **D. All of these**.