Idioblasts are

Options

A. sclerenchymatous fibres found in the leaf of Yucca
B. specialised parenchymatous cells which contains ergastic substances
C. Collenchymatous cells possessing angular thickenings
D. crystals of calcium oxalate found in hard fruits

Explanation

### Step-by-Step Text Solution:

1. **Definition of Idioblasts**: Idioblasts are specialized plant cells that are isolated from the surrounding tissues. They are distinct in structure and function compared to the neighboring cells.

2. **Characteristics of Idioblasts**: These cells differ from the surrounding tissues in various ways, including their function and the substances they store.

3. **Functions of Idioblasts**: The primary function of idioblasts is storage. They serve as reserves for various materials that the plant may need.

4. **Types of Materials Stored**:
- **Excretory Materials**: Idioblasts can store waste products that the plant needs to excrete.
- **Pigments**: They may contain various pigments that contribute to the color of plant tissues.
- **Minerals**: Idioblasts can also store essential minerals that are crucial for the plant's growth and development.
- **Other Substances**: They may contain oils, latex, gum, resin, tannins, and other pigments.

5. **Presence of Crystals**: Some idioblasts contain crystals, which can include:
- **Calcium Oxalate**: Often found in the form of raphides or druses and can be poisonous.
- **Silica**: Sometimes present in idioblasts, contributing to the structural integrity of the plant.

6. **Relation to Other Plant Tissues**: Idioblasts can be considered a type of specialized parenchyma. They are not to be confused with sclerenchyma or collenchyma, which have different functions and characteristics.

7. **Examples**: An example of idioblasts can be found in the leaves of yucca, where they may be associated with storage functions.