Hard and stony shells of fruits and seed coats are characterized by the presence of:

Options

A. collenchyma
B. thick-walled parenchyma
C. sclerenchymatous fibres
D. sclereids

Explanation

To solve the question regarding the hard and stony shells of fruits and seed coats, we need to analyze the options provided and identify which one is responsible for the characteristics described.

### Step-by-Step Solution:

1. **Understand the Question**:
The question asks about the structural components that characterize the hard and stony shells of fruits and seed coats.

2. **Analyze Option 1: Collenchyma**:
- Collenchyma is a type of tissue that provides support and flexibility, mainly found in young stems and leaves.
- It is not responsible for the hardness of shells.
- **Conclusion**: This option is ruled out.

3. **Analyze Option 2: Thick Walled Parenchyma**:
- Parenchyma cells are typically thin-walled and are involved in storage and metabolic functions.
- While there are thick-walled parenchyma cells, they do not contribute to the hardness of shells.
- **Conclusion**: This option is ruled out.

4. **Analyze Option 3: Sclerenchymatous Fibers**:
- Sclerenchyma is a type of tissue that provides structural support, but it is primarily found in the cortex of stems and leaves.
- Although it contributes to strength, it is not specifically responsible for the hard and stony nature of fruit and seed coats.
- **Conclusion**: This option is ruled out.

5. **Analyze Option 4: Sclerites**:
- Sclerites are specialized cells that have thickened, lignified cell walls.
- They are known for providing hardness and rigidity, which is characteristic of the hard and stony shells of fruits and seed coats.
- **Conclusion**: This is the correct option.

6. **Final Answer**:
The hard and stony shells of fruits and seed coats are characterized by the presence of **sclerites**.