External protective tissues of plants are

Options

A. Cork and pericycle.
B. Cortex and epidermis
C. Pericycle and cortex
D. Epidermis and cork

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the external protective tissues of plants. We need to identify which of the given options consist of tissues that serve this protective function on the outside of the plant.

2. **Defining the Terms**:
- **Epidermis**: This is a single layer of cells that covers all plant organs such as leaves, flowers, and roots. It acts as a boundary between the plant's internal system and the external environment, providing protection against physical damage and pathogens.
- **Cork**: This is a tissue found in many vascular plants, formed from the cork cambium. It is involved in secondary growth and replaces the epidermis in stems and roots, providing additional protection.
- **Pericycle**: This is a layer of cells located inside the endodermis and does not serve a protective function on the outside of the plant. It is involved in the formation of lateral roots and does not protect the plant from external factors.
- **Cortex**: This is a layer of unspecialized cells located between the epidermis and the vascular tissues. It does not have a specific protective function and is not exposed to the external environment.

3. **Analyzing the Options**:
- **Option 1: Cork and Pericycle**: Cork is protective, but pericycle is not external.
- **Option 2: Cortex and Epidermis**: Epidermis is protective, but cortex is not external.
- **Option 3: Pericycle and Cortex**: Neither of these is protective on the outside.
- **Option 4: Epidermis and Cork**: Both of these tissues serve as protective layers on the outside of the plant.

4. **Conclusion**: Based on the definitions and analysis, the external protective tissues of plants are **Epidermis and Cork**. Therefore, the correct answer is **Option 4**.

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