A: Due to bottle neck effect, among the survivors, certain alleles may be over-represented, some may be under-represented and some alleles may be totally eliminated.
R: The path extinction of a species cannot be reversed due to bottle neck effect.

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 falses statements, then mark (4)

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that due to the bottleneck effect, among the survivors of a population, certain alleles may be over-represented, some may be under-represented, and some alleles may be completely eliminated.
- The bottleneck effect occurs when a significant reduction in population size happens due to events such as natural disasters (e.g., earthquakes, floods). This leads to a loss of genetic diversity.

**Hint**: Consider how a sudden decrease in population size affects genetic variation.

2. **Analyzing the Reason (R)**:
- The reason states that the path to extinction of a species cannot be reversed due to the bottleneck effect.
- Once a species has gone through a bottleneck, the genetic diversity is reduced, and the alleles present in the remaining population may not represent the original population. This loss of genetic variation can hinder the species' ability to adapt to future environmental changes.

**Hint**: Think about the implications of losing genetic diversity on a species' survival.

3. **Evaluating the Truth of Both Statements**:
- Both the assertion and the reason are true statements. The assertion accurately describes the consequences of the bottleneck effect on allele frequencies, while the reason correctly states that extinction is irreversible once it has occurred.

**Hint**: Reflect on whether both statements are factually correct and how they relate to each other.

4. **Determining the Relationship Between A and R**:
- Although both statements are true, the reason does not explain the assertion. The assertion discusses the changes in allele frequencies due to the bottleneck effect, while the reason talks about extinction being irreversible, which does not directly explain why certain alleles are over or under-represented.

**Hint**: Consider if the reason provides a direct explanation for the assertion or if it merely states another fact.

5. **Conclusion**:
- The correct answer is that both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

**Final Answer**: Option 2: Assertion and reason are true, but the reason is not the correct explanation of the assertion.