Chromosome therory of XY sex determination Was proposed by

Options

A. Henking
B. Wilson and stevens
C. Johannsen
D. Punnet

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the proposal of the chromosome theory of XY sex determination. We need to identify the scientist or scientists who proposed this theory.

2. **Identifying Key Scientists**: From the options provided (Hanking, Wilson and Stevens, Johansson, Punnett), we need to focus on the contributions of Wilson and Stevens, as they are mentioned in the context of sex determination.

3. **Research Contributions**:
- **Stevens' Contribution**: Nettie Stevens conducted research on mealworms and discovered that males produced reproductive cells with both X and Y chromosomes, while females produced only X chromosomes. This led her to conclude that sex is determined by chromosomal factors.
- **Wilson's Contribution**: Edmund Wilson made similar observations around the same time as Stevens, reinforcing the idea that sex determination is linked to chromosomes.

4. **Conclusion**: Although both Stevens and Wilson contributed to the understanding of sex determination, Nettie Stevens is often credited with the initial discovery, while Wilson supported and expanded upon her findings. However, the question specifically asks for the proposal of the theory, which is attributed to Wilson and Stevens collectively.

5. **Final Answer**: The correct answer is **Wilson and Stevens**.

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