Bt toxin is produced by a bacterium called Bacillus thuringiensis ( Bt for short). These Bt toxin crystals contain by a gene named cry which has many variants. Which one from the following produces a toxin that controls corn borer ?

Options

A. CryIAc
B. CryIAb
C. CryIIAb
D. Both (A) and (C)

Answer

To solve the question regarding which variant of the Bt toxin produced by Bacillus thuringiensis controls the corn borer, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Source of Bt Toxin**:
- Bt toxin is produced by the bacterium Bacillus thuringiensis, which is known for its insecticidal properties.

2. **Identify the Gene Variants**:
- The Bt toxin crystals contain a gene named "cry" which has several variants. Each variant encodes a different protein that targets specific pests.

3. **Focus on the Corn Borer**:
- The question specifically asks for the variant that controls the corn borer.

4. **Review the Variants**:
- The variants mentioned include:
- Cry1Ac: Controls cotton bollworm.
- Cry1Ab: This variant is known to control the corn borer.
- Other variants may control different pests but are not relevant to the corn borer.

5. **Select the Correct Option**:
- Based on the information, the correct variant that produces a toxin to control the corn borer is Cry1Ab.

### Final Answer:
The variant that produces a toxin that controls the corn borer is **Cry1Ab**.

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