The technique of hydroponics was first demonstated by

Options

A. M. Calvin (1961)
B. Julium von sachs (1860)
C. Arnon (1940)
D. Hoagland (1940)

Answer

### Step-by-Step Solution:

1. **Understanding Hydroponics**: Hydroponics is a method of growing plants without soil, using a nutrient-rich water solution instead. It allows for the efficient delivery of nutrients directly to the plant roots.

2. **Identifying the Scientist**: The question asks who first demonstrated the technique of hydroponics. This requires knowledge of historical figures in botany and agricultural science.

3. **Researching Historical Contributions**: The technique of hydroponics was first demonstrated by a scientist named Julius von Sachs in 1860. He is known for his work in plant nutrition and is often credited with developing the standard nutrient solution used in hydroponics.

4. **Confirming the Details**: Julius von Sachs was a professor of botany at the University of Würzburg, where he conducted his research on plant nutrition and hydroponics.

5. **Final Answer**: The correct answer to the question is Julius von Sachs.