Growth in living being is by

Options

A. Cell division
B. Cell elongation
C. Cell differentiation
D. All the above

Answer

### Step-by-Step Solution:

1. **Understanding Growth**:
- Growth in living beings is defined as an irreversible increase in size. This means that once an organism grows, it cannot revert to its previous size.

2. **Stages of Plant Growth**:
- Plant growth consists of three main developmental stages:
- **Cell Division**: This is the first stage where the number of cells increases. In plants, this involves two processes: karyokinesis (division of the nucleus) followed by cytokinesis (division of the cytoplasm).
- **Cell Elongation**: This is the second stage where the cells increase in size, contributing to the overall growth of the plant's organs and tissues.
- **Cell Differentiation**: This is the third stage where the newly formed cells take on specific functions, becoming specialized for various roles within the organism.

3. **Conclusion**:
- Therefore, growth in living beings occurs through a combination of cell division, cell elongation, and cell differentiation. The correct answer to the question is that growth in living beings is by all of the above processes.