Some of the characteristics of Bt cotton are

Options

A. long fibre and resistance to aphids
B. medium yield, long fibre and resistance to beetle pests
C. high yield and production of toxic protein crystals which kill dipteran pests
D. high yield and resistance to bollworms

Answer

### Step-by-Step Solution:

1. **Understanding Bt Cotton**:
- Bt cotton is a genetically modified organism (GMO) that has been engineered to express a specific protein from the bacterium *Bacillus thuringiensis* (Bt). This protein is known for its insecticidal properties.

2. **Transgenic Crop Definition**:
- A transgenic crop is one that has had a foreign gene inserted into its genome. In the case of Bt cotton, the gene responsible for producing the Bt toxin has been incorporated into the cotton plant.

3. **Mechanism of Action**:
- The Bt toxin is produced in an inactive form in the bacterium. When insects consume the cotton plant, the alkaline conditions in their gut activate the toxin, which then disrupts their digestive system, leading to their death.

4. **Characteristics of Bt Cotton**:
- **Pest Resistance**: Bt cotton is specifically designed to be resistant to certain pests, particularly the cotton bollworm, which is a significant threat to cotton crops.
- **High Yield**: By reducing pest damage, Bt cotton can lead to higher yields compared to non-Bt cotton varieties.
- **Reduced Need for Chemical Pesticides**: Since Bt cotton naturally produces its own pest resistance, farmers may rely less on chemical pesticides, which can be beneficial for the environment.

5. **Conclusion**:
- The primary characteristics of Bt cotton include its ability to produce the Bt toxin, which provides resistance to pests like the cotton bollworm, and its potential for higher yield due to reduced pest damage.

### Final Answer:
Some of the characteristics of Bt cotton include:
- Resistance to cotton bollworm and other pests.
- High yield due to reduced pest damage.
- Reduced reliance on chemical pesticides.

---