The twin characters of growth are

Options

A. Decrease in mass and increase in number
B. Increase in mass and decrease in number
C. Decrease in mass and number
D. Increase in mass and number

Answer

To answer the question "The twin characters of growth are," we need to analyze the options provided and determine which pair of characteristics aligns with the concept of growth in biological terms.

### Step-by-Step Solution:

1. **Understand Growth in Biology**: Growth in biological terms refers to an increase in size, mass, and number of organisms. It typically involves both an increase in the mass of individual organisms and an increase in the population size.

2. **Evaluate the Options**:
- **Option A**: Decrease in mass and increase in number.
- Analysis: A decrease in mass indicates negative growth for an individual, even if the population size increases. This does not represent growth positively.
- **Option B**: Increase in mass and decrease in number.
- Analysis: While an increase in mass is positive for individuals, a decrease in population size negatively impacts overall growth. This option is incorrect.
- **Option C**: Decrease in mass and number.
- Analysis: Both mass and number decreasing indicates negative growth. This option is also incorrect.
- **Option D**: Increase in mass and number.
- Analysis: This option indicates that both individual organisms are growing (increasing in mass) and the population is also increasing in size. This represents positive growth in both aspects.

3. **Conclusion**: After analyzing all options, the correct answer is **Option D: Increase in mass and number**, as it reflects the twin characters of growth positively.

### Final Answer:
The twin characters of growth are **increase in mass and increase in number** (Option D).