Which of the following nematode infects the roots of tobacco plant and causes a great reduction in yield.

Options

A. Bacillus thuringiensis
B. Ascaris lumbricoides
C. Wuchereria malayi
D. Meloidogyne incognita

Answer

To solve the question regarding which nematode infects the roots of the tobacco plant and causes a significant reduction in yield, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a specific nematode that affects tobacco plants and reduces their yield.

2. **Identify the Options**: The options provided likely include various nematodes and other organisms. We need to focus on nematodes that are known to affect plants.

3. **Recall Relevant Information**:
- Nematodes are a type of roundworm, and some species are known to be plant pathogens.
- The nematode that is particularly known for infecting tobacco plants is *Meloidogyne incognita*.

4. **Evaluate Other Options**:
- *Bacillus thuringiensis* is a bacterium used for pest control, not a nematode.
- *Ascaris lumbricoides* is a human intestinal parasite, unrelated to plants.
- *Wuchereria bancrofti* causes filariasis in humans, not related to plant infections.

5. **Confirm the Correct Answer**: Based on the information gathered, *Meloidogyne incognita* is indeed the nematode that infects the roots of tobacco plants and leads to a reduction in yield.

6. **Final Answer**: The correct answer is *Meloidogyne incognita*.