Classification of plastids is mainly based on

Options

A. Shape
B. Size
C. Pigmentation
D. Ontogeny

Answer

### Step-by-Step Solution:

1. **Understanding Plastids**: Plastids are double membrane-bound organelles found in plants and some algae. They play a crucial role in various functions, including photosynthesis and storage.

2. **Types of Plastids**: There are three major types of plastids:
- **Chloroplasts**: These contain chlorophyll, the green pigment essential for photosynthesis.
- **Chromoplasts**: These contain various colorful pigments (like xanthophyll and carotenoids) that give color to fruits and flowers.
- **Leucoplasts**: These are colorless plastids primarily involved in the storage of food. They can be further classified into:
- **Amyloplasts**: Store starch.
- **Elaioplasts**: Store oils.
- **Proteoplasts**: Store proteins.

3. **Classification Basis**: The classification of plastids is mainly based on the pigments they contain:
- Chloroplasts (green pigment - chlorophyll)
- Chromoplasts (various colored pigments)
- Leucoplasts (colorless, for storage)

4. **Evaluating Options**: The question provides options: shape, size, pigmentation, and ontogenic.
- **Shape**: Incorrect, as plastids can have similar shapes.
- **Size**: Incorrect, as size does not determine the type.
- **Pigmentation**: Correct, as the classification is based on the pigments present.
- **Ontogenic**: Incorrect, as this refers to the developmental history, not classification.

5. **Conclusion**: Therefore, the correct answer to the question "Classification of plastids is mainly based on" is **pigmentation**.