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 yields and resistance to bollworms

Explanation

### Step-by-Step Solution:

1. **Understanding Bt Cotton**:
- Bt cotton is a genetically modified organism (GMO) that incorporates a gene from the bacterium *Bacillus thuringiensis* (Bt).
- This bacterium produces a protein known as the Bt toxin, which is toxic to certain pests.

2. **Function of Bt Toxin**:
- The Bt toxin specifically targets and kills insects such as Lepidopterans (e.g., cotton bollworm), Dipterans, and Coleopterans.
- This helps in protecting the cotton plants from these harmful pests, leading to healthier crops.

3. **Key Characteristics of Bt Cotton**:
- **High Yield**: Bt cotton generally has a higher yield compared to non-Bt cotton because it suffers less damage from pests.
- **Resistance to Pests**: Bt cotton is particularly resistant to the cotton bollworm, which is a significant pest for cotton crops.
- **Production of Toxic Protein**: The plant produces the Bt toxin, which acts as an insecticide, protecting it from pest infestations.

4. **Cry Genes**:
- The production of the Bt toxin in cotton is due to the presence of specific genes known as Cry genes, specifically Cry1AB and Cry2AB.
- Cry1AB provides protection against the corn borer, while Cry2AB protects against cotton bollworm.

5. **Conclusion**:
- The main characteristics of Bt cotton include high yield and resistance to pests, particularly the cotton bollworm, due to the production of the Bt toxin.

### Final Answer:
Some of the characteristics of Bt cotton are:
- High yield
- Resistance to cotton bollworm
- Production of the Bt toxin which acts as an insecticide.

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