In leguminous plant root nodules are formed due to division and cells division of:

Options

A. Cortex
B. Pericycle
C. Both
D. Xylem and phloem

Answer

To answer the question regarding the formation of root nodules in leguminous plants, we can break down the process into clear steps:

### Step-by-Step Solution:

1. **Understanding Root Nodules**: Root nodules are specialized structures found in leguminous plants that house nitrogen-fixing bacteria, primarily Rhizobium. These nodules play a crucial role in the nitrogen cycle by converting atmospheric nitrogen into a form that plants can use.

2. **Initiation of Nodule Formation**: The process begins when Rhizobium bacteria come into contact with the root hairs of leguminous plants. The bacteria attach to the root hairs and begin to multiply.

3. **Bacterial Infection**: Once the bacteria are attached, they induce the root hair to curl, which allows the bacteria to enter the root through a structure known as an infection thread. This infection thread is formed as the root hair cells divide and elongate.

4. **Cell Division in the Plant**: After the bacteria enter the root, they travel through the infection thread to the cortical and pericycle regions of the root. Here, the presence of the bacteria stimulates the plant cells to divide.

5. **Formation of Nodules**: The division of the plant cells in the cortex and pericycle leads to the formation of root nodules. These nodules provide a habitat for the bacteria and facilitate the exchange of nutrients between the plant and the bacteria.

6. **Conclusion**: The correct answer to the question is that the formation of root nodules in leguminous plants is due to the division of both the plant cells (in the cortex and pericycle) and the bacterial cells (Rhizobium). Therefore, the answer is option 3, which states "both".