Accretionary growth is due to
(a) Reserve cells
(b) Meristematic cells
(c) Embryonic cells
(d) Differentiated cells

Options

A. Reserve cells
B. Meristematic cells
C. Embryonic cells
D. Differentiated cells

Answer

To solve the question regarding what accretionary growth is due to, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Accretionary Growth**:
- Accretionary growth, also referred to as post-embryonic growth, occurs after the embryonic stage of an organism's development. This type of growth is significant in the adult stage of organisms.

2. **Identify the Types of Cells Mentioned**:
- The options provided are:
- (a) Reserve cells
- (b) Meristematic cells
- (c) Embryonic cells
- (d) Differentiated cells

3. **Analyze Each Option**:
- **Reserve Cells**: These cells can divide and contribute to growth in adult organisms, particularly in certain tissues.
- **Meristematic Cells**: These are undifferentiated cells found in plants that can divide and differentiate into various cell types. They are primarily responsible for primary and secondary growth in plants.
- **Embryonic Cells**: These cells are involved in the early stages of development and are not responsible for post-embryonic growth.
- **Differentiated Cells**: These cells have already undergone differentiation and typically do not divide or contribute to growth.

4. **Determine the Correct Answer**:
- Since accretionary growth occurs in the adult stage and involves cells that can still divide (albeit limited), the most suitable option is **(a) Reserve cells**. These cells can still undergo mitosis to form the necessary structures for growth.

5. **Conclusion**:
- Therefore, the correct answer to the question is **(a) Reserve cells**.