Actually, the Bt toxin protein exist as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the :-

Options

A. Acidic pH of the gut
B. Alkaline pH of the gut
C. Neutral pH of the gut
D. Either acidic or alkaline pH of the gut

Answer

To answer the question regarding the conversion of the inactive Bt toxin protein into its active form upon ingestion by an insect, we can break down the process into the following steps:

### Step-by-Step Solution:

1. **Understanding Bt Toxin**: The Bt toxin, derived from the bacterium *Bacillus thuringiensis*, exists in an inactive form known as a protoxin. This form is not harmful to insects or other organisms.

2. **Ingestion by Insects**: When an insect consumes a plant that has been genetically modified to express this Bt toxin, it ingests the inactive protoxin.

3. **Location of Activation**: The conversion of the inactive protoxin to its active form occurs in the midgut of the insect. The midgut is the part of the digestive system where food is processed and nutrients are absorbed.

4. **pH Environment**: The key factor for the conversion is the pH level in the insect's midgut. Insects typically have a midgut that maintains an alkaline pH, which is higher than neutral (around 11).

5. **Conversion Process**: The alkaline conditions in the midgut facilitate the proteolytic cleavage of the protoxin, resulting in the formation of the active toxin. This active form is now capable of binding to specific receptors in the gut cells of the insect.

6. **Effect of Active Toxin**: Once activated, the toxin disrupts the gut cells, leading to the death of the insect due to starvation or septicemia.

7. **Conclusion**: Therefore, the reason the inactive Bt toxin is converted into its active form is due to the alkaline pH of the insect's gut.

### Final Answer:
The conversion of the inactive Bt toxin protein into its active form occurs due to the **alkaline pH of the gut**.

---