The strategy used to prevent the nematode infection in the roots of tobacoo plant in called:

Options

A. use of agrocchemicals
B. Bt toxin gene
C. gene mutation
D. RNA interference

Answer

To solve the question regarding the strategy used to prevent nematode infection in the roots of the tobacco plant, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Problem**: The question asks about a specific strategy used to prevent nematode infection in tobacco plants. Nematodes, particularly *Meloidogyne incognita*, are known to infect the roots of tobacco plants and cause significant damage.

2. **Understand Nematode Infection**: Nematodes are parasitic organisms that can affect various plants, leading to reduced growth and yield. In the case of tobacco, *Meloidogyne incognita* is a common nematode that infests the roots.

3. **Evaluate the Options**: The options provided are:
- Use of agrochemicals
- Bt toxin gene
- Gene mutation
- RNA defense technology

4. **Analyze RNA Defense Technology**: Among the options, RNA interference (RNAi) technology is a biotechnological method that can be used to silence specific genes. It involves the introduction of a complementary RNA strand that binds to the target RNA, preventing the production of proteins necessary for the nematode's survival and reproduction.

5. **Conclude the Correct Answer**: Based on the analysis, the strategy used to prevent nematode infection in the roots of tobacco plants is called **RNA interference technology**.

### Final Answer:
The strategy used to prevent the nematode infection in the roots of the tobacco plant is called **RNA interference technology**.

---