Evolution -
A. Is descent with modification .
B. Is gradual for Darwin
C. Is a change , in the frequency of an allete within a population , caused by differential reproduction in response to local environmental conditions.
D. Is irreversible

Options

A. A and B are correct
B. C and D are correct
C. All are correct
D. None are correct

Answer

To analyze the question regarding evolution, we will evaluate each statement (A, B, C, D) to determine which ones are correct based on the principles of evolutionary biology.

### Step-by-Step Solution:

1. **Evaluate Statement A**:
- Statement A claims that "Evolution is descent with modification."
- This statement aligns with Charles Darwin's definition of evolution. He proposed that species evolve over time through a process where descendants differ from their ancestors due to modifications.
- **Conclusion**: Statement A is **correct**.

2. **Evaluate Statement B**:
- Statement B states that "Evolution is gradual for Darwin."
- Darwin emphasized that evolution occurs gradually over long periods. He described the process as a slow and continuous change, leading to the formation of new species.
- **Conclusion**: Statement B is **correct**.

3. **Evaluate Statement C**:
- Statement C claims that "Evolution is a change in the frequency of an allele within a population, caused by differential reproduction in response to local environmental conditions."
- While this statement describes a mechanism of evolution known as natural selection, it does not encompass the broader definition of evolution itself. Evolution is more than just allele frequency changes; it includes the overall process of descent with modification.
- **Conclusion**: Statement C is **incorrect**.

4. **Evaluate Statement D**:
- Statement D states that "Evolution is irreversible."
- This statement is misleading. Evolution can lead to changes that may not be reversed, but it does not mean that all evolutionary changes are irreversible. Some traits can be lost or regained over time.
- **Conclusion**: Statement D is **incorrect**.

### Final Conclusion:
Based on the evaluations:
- Statements A and B are correct.
- Statements C and D are incorrect.