Growth in living organisms occurs by

Options

A. Division of cells
B. Increase in mass of the living structure
C. Accumulation of material by external agency
D. Both (1) & (2)

Explanation

To answer the question "Growth in living organisms occurs by," we will analyze the options provided and determine the correct ones based on biological principles.

### Step-by-Step Solution:

1. **Understanding Growth in Living Organisms**:
- Growth in living organisms refers to an increase in size, mass, or number of cells in an organism.

2. **Option Analysis**:
- **Option A: Division of Cells**:
- This is a fundamental process in growth. When cells divide (through processes like mitosis), they create new cells, which contribute to the overall growth of the organism. Therefore, this option is correct.

- **Option B: Increase in the Mass of Living Structure**:
- As cells divide and new cells are formed, the overall mass of the organism increases. This is also a correct statement regarding growth.

- **Option C: Accumulation of Material by External Agency**:
- This option suggests that growth occurs through external means, which is not a primary mechanism of growth in living organisms. Growth is primarily an internal process driven by cell division and metabolic activities. Thus, this option is incorrect.

3. **Conclusion**:
- Based on the analysis, options A and B are correct. Therefore, the correct answer to the question is that growth in living organisms occurs by both the division of cells and the increase in the mass of living structures.

### Final Answer:
Growth in living organisms occurs by:
- A) Division of cells
- B) Increase in the mass of living structures