Which of the following crops till now has been genetically modified?

Options

A. Tobacco
B. Tomato
C. Cotton
D. All of these

Answer

To determine which of the following crops has been genetically modified, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the crops listed in the options**: The options given are:
- Tobacco
- Tomato
- Cotton
- All of the above

2. **Examine the genetic modification of Tobacco**:
- Tobacco has been genetically modified to prevent insect attacks by introducing a foreign gene known as the cry gene. This modification helps in making the plant resistant to pests.

3. **Examine the genetic modification of Tomato**:
- The tomato has been genetically altered to create a variety known as "Flavr Savr" tomato. This modification delays the ripening process, allowing the tomato to maintain its taste for a longer period.

4. **Examine the genetic modification of Cotton**:
- Cotton has also been genetically modified to enhance its resistance to pests, specifically the cotton bollworm. This is achieved by introducing the cry gene, which helps in making the cotton plant resistant to these pests.

5. **Conclusion**:
- Since all three crops (Tobacco, Tomato, and Cotton) have been genetically modified, the correct answer to the question is "All of the above."

### Final Answer:
The correct option is **4. All of the above**.

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