[A]: Darwin held that small favourable varia- tions formed the raw material for evolution.
[R]: Darwin did not go into the factors which produce variations

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

To analyze the statements regarding Darwin's views on evolution and variations, we can break down the question into two parts: the assertion [A] and the reason [R].

### Step-by-Step Solution:

1. **Understanding Assertion [A]:**
- Darwin proposed that small favorable variations are essential for the process of evolution. These variations provide the necessary raw material for natural selection to act upon.
- Example: In a population of animals, those with slight variations that make them better suited to their environment (like thicker fur in colder climates) are more likely to survive and reproduce.

2. **Understanding Reason [R]:**
- The reason states that Darwin did not delve into the factors that produce these variations. This implies that while he recognized the importance of variations, he did not explain how they arise.
- Example: Darwin acknowledged that variations exist but did not explore genetic mechanisms or environmental influences that could lead to these variations.

3. **Evaluating the Relationship Between [A] and [R]:**
- The assertion [A] is true: small favorable variations do indeed form the basis for evolution according to Darwin's theory of natural selection.
- The reason [R] is also true: Darwin did not provide a detailed explanation of the factors that produce variations.
- However, the reason [R] does not adequately explain the assertion [A]. The assertion stands on its own merit regarding the role of variations in evolution, regardless of whether Darwin discussed their origins.

4. **Conclusion:**
- Both the assertion and the reason are true statements, but the reason does not correctly justify the assertion. Therefore, while [A] is valid, [R] does not serve as a proper explanation for it.

### Final Answer:
- Assertion [A] is true; small favorable variations are indeed the raw material for evolution.
- Reason [R] is true but does not explain [A].