The nematode that infects the root of tobacco plants and causes a great reduction in its yield is:

Options

A. Ancylostoma duodenale
B. Meloidegyne incognita
C. Wuchereria bancrofri
D. Ascaris lumbricoides

Answer

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

### Step 1: Understand the Question
The question asks for a specific nematode that affects tobacco plants. We need to identify the correct nematode from the given options.

### Step 2: Analyze the Options
The options provided are:
1. Encyclostoma
2. Melidogyne incognita
3. Guterria Bencroft
4. Ascaris labrycoides

### Step 3: Identify the Correct Nematode
Among the options, **Melidogyne incognita** is known as the root-knot nematode. This nematode is notorious for infecting the roots of various plants, including tobacco, and is responsible for significant yield losses.

### Step 4: Confirm the Impact
The root-knot nematode (Melidogyne incognita) causes the formation of galls on the roots, which disrupts the plant's ability to absorb water and nutrients, leading to reduced growth and yield.

### Step 5: Conclusion
Based on the analysis, the correct answer to the question is **Melidogyne incognita**.