showed that in the presence of sunlight only the green parts of the plants could release oxygen

Options

A. Julius Von Sachs
B. Joseph Priestley
C. Jan Ingenhousz
D. Van Niel

Answer

To solve the question, we need to identify who demonstrated that only the green parts of plants can release oxygen in the presence of sunlight. Let's analyze the options provided:

1. **Julius Von Sachs**: He contributed to our understanding of photosynthesis by providing evidence for the production of glucose in plants. However, he did not specifically demonstrate the release of oxygen in the presence of sunlight.

2. **Joseph Priestley**: He is known for his experiments that showed the necessity of oxygen for the survival of living organisms. He conducted an experiment with a candle and a plant in a jar, which indicated that plants produce oxygen, but he did not specifically focus on the green parts of the plant.

3. **Jan Ingenhousz**: He is the key figure in this context. Ingenhousz conducted experiments with aquatic plants and demonstrated that in the presence of sunlight, only the green parts of the plants release oxygen. His work showed that sunlight is essential for the process of photosynthesis and the release of oxygen.

4. **Van Neel**: He studied photosynthesis and demonstrated that it is a light-dependent process, but he did not specifically address the role of green parts in oxygen release.

Based on this analysis, the correct answer to the question is **Jan Ingenhousz**.

### Step-by-Step Solution:
1. **Identify the Question**: The question asks who showed that only the green parts of plants could release oxygen in the presence of sunlight.

2. **Review the Options**: Look at the contributions of each individual mentioned in the options.

3. **Analyze Julius Von Sachs**: He focused on glucose production, not specifically on oxygen release.

4. **Analyze Joseph Priestley**: He demonstrated the need for oxygen but did not focus on the green parts of plants.

5. **Analyze Jan Ingenhousz**: He conducted experiments that specifically showed that only the green parts of plants release oxygen when exposed to sunlight.

6. **Analyze Van Neel**: He discussed photosynthesis as a light-dependent process but did not specifically address oxygen release from green parts.

7. **Conclude**: Based on the analysis, Jan Ingenhousz is the correct answer.

### Final Answer:
**Jan Ingenhousz**