Assertion: Agriculture and aquacultures are man-maintained ecosystems.
Reason: All biotic and abiotic factors are managed by humans in these ecosystems.

Options

A. If both Assertion and Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion and Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true but Reason is false, then mark (3).
D. If both Assertion and Reason are false, then mark (4)

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that agriculture and aquaculture are man-maintained ecosystems.
- Agriculture involves the cultivation of crops and livestock, while aquaculture refers to the farming of aquatic organisms like fish, shellfish, and plants in controlled environments.

2. **Analyzing the Reason**:
- The reason given is that all biotic (living organisms) and abiotic (non-living environmental factors) factors are managed by humans in these ecosystems.
- Biotic factors include plants, animals, and microorganisms, which can be managed to some extent by human intervention (e.g., selective breeding, pest control).
- Abiotic factors include elements like temperature, sunlight, water, and soil composition.

3. **Evaluating the Control Over Abiotic Factors**:
- While humans can influence some abiotic factors (e.g., irrigation systems can manage water supply), many abiotic factors are beyond human control (e.g., climate changes, natural disasters).
- Therefore, the statement that all abiotic factors are managed by humans is incorrect.

4. **Conclusion**:
- The assertion is true because agriculture and aquaculture are indeed man-maintained ecosystems.
- The reason is false because not all abiotic factors can be managed by humans.
- Thus, the correct relationship is that the assertion is true, and the reason is false.

5. **Final Answer**:
- The correct option is: The assertion is true, but the reason is false.