Who provided the evidence that glucose is formed during photosynthesis and is then stored in the form of starch?

Options

A. Sachs
B. Engelmann
C. van Niel
D. Blackmann

Explanation

To answer the question of who provided the evidence that glucose is formed during photosynthesis and is then stored in the form of starch, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Key Concept**: The question is asking about the scientist who demonstrated that glucose is produced during photosynthesis and later stored as starch.

2. **Historical Context**: In the mid-19th century, there was limited understanding of the biochemical processes involved in photosynthesis, including the formation of glucose and its storage.

3. **Research the Relevant Scientist**: The scientist who provided significant evidence regarding the formation of glucose during photosynthesis and its storage as starch is Julius von Sack.

4. **Summarize the Contribution**: Julius von Sack conducted experiments in 1854 that led to the conclusion that during photosynthesis, plants convert light energy into chemical energy in the form of glucose, which is subsequently stored as starch.

5. **Conclude the Answer**: Therefore, the answer to the question is Julius von Sack.

### Final Answer:
Julius von Sack provided the evidence that glucose is formed during photosynthesis and is then stored in the form of starch.