Darwin's theory states that

Options

A. Charaters are acquired through inheritance
B. Species change morphologically with time
C. Nature selects organisms which can adapts
D. Evolution is due to effect of environment

Answer

### Step-by-Step Text Solution:

1. **Understanding Darwin's Theory**: Darwin's theory of evolution primarily revolves around the concept of natural selection. This theory suggests that organisms undergo genetic changes over time, which leads to the evolution of species.

2. **Key Phrase**: A crucial phrase associated with Darwin's theory is "survival of the fittest." This phrase encapsulates the idea that individuals best adapted to their environment are more likely to survive and reproduce.

3. **Natural Selection**: According to Darwin, natural selection is the mechanism through which evolution occurs. It implies that traits that enhance survival and reproduction become more common in successive generations of a population.

4. **Evaluating the Options**:
- **Option 1**: "Characters are acquired through inheritance." This is incorrect as Darwin's theory does not focus on acquired characteristics.
- **Option 2**: "Species change morphologically with time." While species do change, Darwin's theory emphasizes genetic changes rather than just morphological changes.
- **Option 3**: "Nature selects organisms which can adapt." This aligns with Darwin's theory, making it the correct choice.
- **Option 4**: "Evolution is due to the effect of the environment." While the environment plays a role, this statement is too broad and does not accurately reflect Darwin's emphasis on natural selection.

5. **Conclusion**: The correct answer to the question is Option 3: "Nature selects organisms which can adapt," as it accurately reflects the essence of Darwin's theory of evolution through natural selection.