Bt-cotton has which of the following special feature ?

Options

A. This plant is completely resistant to insects
B. It requires less fertilizers
C. It's leaf is resistant to pest but doll is destroyed by bollworms
D. This plant is resistant to certain insects

Answer

**Step-by-Step Solution:**

1. **Understanding Bt Cotton**: Bt cotton is a genetically modified variety of cotton that has been engineered to express a protein from the bacterium *Bacillus thuringiensis* (Bt). This protein is toxic to certain insects that feed on cotton plants.

2. **Identifying Special Features**: The key feature of Bt cotton is its ability to resist specific insect pests, particularly the cotton bollworm, which is a significant threat to cotton crops.

3. **Mechanism of Action**: The Bt toxin produced by Bt cotton works by creating pores in the gut of the insects that consume the cotton. This disrupts their digestive system, leading to their death.

4. **Evaluating Other Options**:
- While it is true that Bt cotton may require less pesticide application due to its insect resistance, the question specifically asks for a special feature of Bt cotton.
- The statement about the leaves being resistant to pests is misleading; the entire plant, including leaves and stems, is designed to resist specific insects.
- The claim that the "doll is destroyed by ball worms" is incorrect as it contradicts the primary feature of Bt cotton being resistant to such pests.

5. **Conclusion**: The correct answer is that Bt cotton is resistant to certain insects, particularly those that are harmful to cotton crops.

**Final Answer**: Bt cotton has the special feature of being resistant to certain insects.

---