Hugo de Vries' contribution is

Options

A. Mutation theory, on the basis of his observation on the wild variety of evening primrose (Oenothera lamarckiana )
B. Theory of natural selection
C. Law of dominance
D. Law of segregation

Answer

### Step-by-Step Solution:

1. **Understanding Hugo de Vries' Contribution**:
- Hugo de Vries is known for his work on the theory of mutation. He proposed that new species arise not through gradual changes as suggested by Darwin, but through sudden and significant changes or mutations.

**Hint**: Focus on the distinction between gradual evolution and sudden changes in species.

2. **The Mutation Theory**:
- De Vries argued that mutations are heritable, meaning they can be passed down to successive generations. This was a significant shift from the idea that species change gradually over time.

**Hint**: Remember that heritability is a key concept in understanding how mutations contribute to evolution.

3. **Experimental Evidence**:
- De Vries conducted experiments on the wild variety of evening primrose (Oenothera lamarckiana). He self-pollinated these plants and observed the offspring.

**Hint**: Think about how experimental evidence supports scientific theories.

4. **Observations from the Experiment**:
- In his observations, he noted that while most of the offspring resembled their parents, some exhibited different traits. These differences suggested the emergence of new species.

**Hint**: Consider the significance of variation in offspring and how it relates to the concept of new species.

5. **Conclusion**:
- From his experiments, de Vries concluded that new species could appear suddenly due to mutations, which could occur without any prior indication of change in the parent species.

**Hint**: Summarize the main takeaway: mutations can lead to the rapid formation of new species.

### Final Answer:
Hugo de Vries' contribution is primarily the formulation of the mutation theory, based on his observations of the wild variety of evening primrose (Oenothera lamarckiana), where he demonstrated that new species can arise from sudden mutations rather than gradual changes.