A: Productivity of eutrophic lake is maximum.
R: Eutrophication is mainly due to addition of `SO_(4^(2-))` and heavy metals.

Options

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

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Analyze the Assertion
The assertion states that "the productivity of eutrophic lake is maximum."

- **Explanation**: Eutrophic lakes are characterized by high biological productivity due to the abundance of nutrients, particularly nitrogen and phosphorus. These nutrients promote the growth of aquatic plants and algae, leading to a rich ecosystem. Therefore, this assertion is **true**.

### Step 2: Analyze the Reason
The reason states that "eutrophication is mainly due to the addition of `SO_(4^(2-)` (sulfate) and heavy metals."

- **Explanation**: Eutrophication is primarily caused by the enrichment of water bodies with nutrients, particularly nitrogen and phosphorus, rather than sulfate and heavy metals. While heavy metals can be pollutants, they do not contribute to the process of eutrophication. Therefore, this reason is **false**.

### Step 3: Conclusion
Based on the analysis:
- The assertion is true.
- The reason is false.

Thus, the correct answer is that the assertion is true, but the reason is false.

### Final Answer
The correct option is that the assertion is true, but the reason is false.

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