Assertion: Population ecology is a link of ecology to population genetics and evolution.
Reason: Natural selection operates at population level to evolve the desired traits.

Options

A. If both Assertion and Reason are true and the reason is correct explanation of the assertion, then mark (1).
B. If both Assertion and Reason are true but the reason are true 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 Population Ecology**:
- Population ecology is a subfield of ecology that focuses on the dynamics of species populations and their interactions with the environment. This includes studying how populations grow, decline, and interact with other species and their habitats.

2. **Link to Population Genetics and Evolution**:
- Population ecology serves as a bridge between ecology and population genetics. It helps in understanding how genetic variations within populations can affect their survival and reproduction, which are crucial for the process of evolution.

3. **Natural Selection at the Population Level**:
- Natural selection is a key mechanism of evolution that operates at the population level. It refers to the process where individuals with favorable traits are more likely to survive and reproduce, passing those traits on to the next generation. This process leads to the evolution of species over time.

4. **Evaluating the Assertion and Reason**:
- The assertion states that "Population ecology is a link of ecology to population genetics and evolution," which is true as it connects the dynamics of populations with genetic and evolutionary processes.
- The reason states that "Natural selection operates at the population level to evolve the desired traits," which is also true as natural selection is a fundamental process that drives evolution.

5. **Conclusion**:
- Both the assertion and the reason are correct. Furthermore, the reason provides a correct explanation for the assertion, as it describes how natural selection influences population dynamics and evolution.

### Final Answer:
Both the assertion and the reason are correct, and the reason is a correct explanation of the assertion.

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