Identify the incorrect statement regarding Bt-cotton.

Options

A. Dried spores of Bacillus thuringiensis are sprayed on its vulnerable leaves
B. It releases toxin that causes swelling in the gut of insect that ingest its leaves
C. It is a tansgenic plant
D. crylAc and cryllAb genes are introduced to make them resistant against ballworms.

Answer

To identify the incorrect statement regarding Bt-cotton, let's analyze the provided statements one by one:

1. **Statement 1**: "The dried spores of the Bacillus thuringiensis are spread on its vulnerable leaves."
- This statement is incorrect. While Bacillus thuringiensis (Bt) is indeed used in Bt-cotton, the dried spores are not simply spread on the leaves. Instead, they are typically formulated into a product that is mixed with water and then sprayed onto the plants. Thus, the statement misrepresents the method of application.

2. **Statement 2**: "It releases a toxin that causes swelling in the gut of the insect that ingests its leaves."
- This statement is correct. Bt-cotton produces a toxin that is harmful to certain insect larvae. When these insects consume the leaves, the toxin is activated in their gut, leading to swelling and ultimately death due to starvation or infection.

3. **Statement 3**: "It is a transgenic plant."
- This statement is also correct. Bt-cotton is a genetically modified organism (GMO) that has been engineered to express the Bt toxin, making it resistant to specific pests.

4. **Statement 4**: "Cry1AC and Cry2AB genes are introduced to make them resistant against the bollworms."
- This statement is correct as well. The Cry1AC and Cry2AB genes from Bacillus thuringiensis are indeed introduced into the cotton plant to confer resistance against various pests, including bollworms.

Based on the analysis, the incorrect statement regarding Bt-cotton is the first one.

### Summary of the Solution:
- The first statement about the application of Bacillus thuringiensis is incorrect.
- The other statements regarding the toxin's effect, the transgenic nature of Bt-cotton, and the specific genes introduced are all correct.