[A]: Isolation is a mechanism which prevents interbreeding among other wise potential mates.
[R]: It is the key factor without which all other factors of evolution will merge into jumble of no significance

Options

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

Answer

### Step-by-Step Solution:

1. **Understanding Isolation**:
- Isolation is defined as a mechanism that prevents interbreeding among potential mates. This can occur due to various barriers, which can be physical, ecological, or geographical.

2. **Types of Isolation**:
- Isolation can be categorized into two main types:
- **Prezygotic Isolation**: This prevents fertilization from occurring.
- Examples include:
- **Temporal Isolation**: Different species reproduce at different times.
- **Behavioral Isolation**: Different mating signals or behaviors.
- **Ecological Isolation**: Species occupy different habitats within the same area.
- **Gametic Isolation**: Sperm and egg are released but do not fertilize each other.
- **Postzygotic Isolation**: This occurs after fertilization and prevents the formation of fertile offspring.

3. **Analyzing the Statements**:
- Statement [A]: "Isolation is a mechanism which prevents interbreeding among otherwise potential mates."
- This statement is true as it accurately describes the role of isolation in preventing interbreeding.
- Statement [R]: "It is the key factor without which all other factors of evolution will merge into a jumble of no significance."
- This statement is also true, but it does not correctly explain the first statement. While isolation is important for maintaining species boundaries, it does not encompass all factors of evolution.

4. **Conclusion**:
- Both statements [A] and [R] are true, but [R] is not the correct explanation for [A]. Therefore, the correct answer is that both [A] and [R] are true, but [R] is not the correct explanation for [A].

### Final Answer:
Both [A] and [R] are true, but [R] is not the correct explanation for [A].

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