Assertion : With the increase in population size, environmental resistance tends to increase.
Reason : This is a nature's way to check the expression of biotic potential.

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Explanation

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that with an increase in population size, environmental resistance tends to increase. Environmental resistance refers to the factors that limit the growth of a population, such as food availability, predation, disease, and natural disasters.

2. **Analyzing the Reason**: The reason given is that this increase in environmental resistance is nature's way to check the expression of biotic potential. Biotic potential is the maximum reproductive capacity of an organism under optimal environmental conditions.

3. **Connecting Assertion and Reason**: As the population size increases, the demand for resources like food, space, and other necessities also increases. When these resources become limited due to the larger population, environmental resistance increases. This is a natural mechanism to prevent overpopulation and ensure that the population remains within the carrying capacity of the environment.

4. **Conclusion**: Both the assertion and the reason are correct. The assertion correctly identifies the relationship between population size and environmental resistance, while the reason explains that this relationship is a natural regulatory mechanism to control population growth.

5. **Final Answer**: Therefore, the correct option is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

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