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 is asking for a specific nematode that affects tobacco plants, leading to reduced yield.

2. **Evaluate the Options**: We have four options to consider:
- **Option 1: Bacillus thuringiensis**
- **Option 2: Ascaris Lumbricoides**
- **Option 3: Vuccaria mellae**
- **Option 4: Maledogine incognita**

3. **Analyze Each Option**:
- **Option 1: Bacillus thuringiensis**: This is a bacterium, not a nematode. Therefore, it cannot be the correct answer.
- **Option 2: Ascaris Lumbricoides**: This is a roundworm that infects humans and causes ascariasis. It does not infect tobacco plants, making this option incorrect.
- **Option 3: Vuccaria mellae**: This is a parasitic worm that causes filariasis, which is unrelated to tobacco plants. Thus, this option is also incorrect.
- **Option 4: Maledogine incognita**: This is a type of nematode known to infect the roots of tobacco plants, leading to a significant reduction in yield. This option is likely the correct answer.

4. **Select the Correct Answer**: Based on the analysis, the correct answer is **Option 4: Maledogine incognita**.

### Final Answer:
The nematode that infects the roots of the tobacco plant and causes a great reduction in yield is **Maledogine incognita**.

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