During secondary growth in a dicot root, cork cambium is formed by the activity of

Options

A. cortex
B. hypodermis
C. pericycle
D. epidermis.

Explanation

To solve the question regarding the formation of cork cambium during secondary growth in a dicot root, follow these steps:

### Step-by-Step Solution:

1. **Understand Secondary Growth**: Secondary growth refers to the increase in thickness or girth of the plant, which occurs in the roots and stems of dicots and some gymnosperms. This growth is facilitated by lateral meristems, particularly the vascular cambium and cork cambium.

2. **Identify the Tissues Involved**: In dicot roots, the main tissues involved in secondary growth include the pericycle, cortex, hypodermis, and epidermis. Each of these tissues has a specific role in the growth process.

3. **Focus on Cork Cambium Formation**: The cork cambium, also known as phellogen, is responsible for producing cork cells that protect the plant. It is important to identify which tissue gives rise to the cork cambium during secondary growth.

4. **Evaluate the Options**:
- **Cortex**: Primarily involved in storage and does not contribute to cork cambium.
- **Hypodermis**: Provides protection but does not form cork cambium.
- **Pericycle**: This is the layer of cells just inside the endodermis and is known to be responsible for the formation of cork cambium during secondary growth.
- **Epidermis**: The outermost layer of cells, which does not contribute to the formation of cork cambium.

5. **Conclude with the Correct Answer**: Since the cork cambium is formed by the activity of the pericycle, the correct answer to the question is **pericycle**.

### Final Answer:
During secondary growth in a dicot root, cork cambium is formed by the activity of **pericycle**.

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