Read the following statements and select the correct option:
(a) Net primary productivity is less than the gross primary productivity
(b) Net primary productivity is equal to the gross primary productivity minus the respiration losses

Options

A. Both (a) and (b) are true.
B. (b) is correct but (a) is false.
C. (a) is correct but (b) is false.
D. Both (a) and (b) are false.

Answer

To solve the question, let's analyze the statements given about net primary productivity (NPP) and gross primary productivity (GPP).

### Step-by-Step Solution:

1. **Understanding Gross Primary Productivity (GPP)**:
- GPP refers to the total amount of organic matter produced by photosynthesis in a given area over a specific time period. It represents the total energy captured by plants.

2. **Understanding Net Primary Productivity (NPP)**:
- NPP is the amount of organic matter that remains after accounting for the energy used by plants for respiration. It is the energy available to the next trophic level (herbivores and decomposers).
- The formula for NPP is:
\[ \text{NPP} = \text{GPP} - \text{Respiration Losses} \]

3. **Analyzing Statement (a)**:
- The statement claims that "Net primary productivity is less than the gross primary productivity."
- Since NPP is derived from GPP by subtracting respiration losses, it is indeed true that NPP is always less than GPP. Therefore, statement (a) is **true**.

4. **Analyzing Statement (b)**:
- The statement claims that "Net primary productivity is equal to the gross primary productivity minus the respiration losses."
- This is exactly the formula we discussed earlier. Therefore, statement (b) is also **true**.

5. **Conclusion**:
- Both statements (a) and (b) are true.
- Therefore, the correct option is: **Both A and B are true**.

### Final Answer:
Both A and B are true.

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