- A Aeroponics
- B Drip irrigation
- C Hydroponics
- D Vermiculture
Correct answer: C. Hydroponics
Explanation: Hydroponics is the technique of growing plants in defined nutrient solutions without soil. It was used by scientists (Knop, Arnon) to discover which mineral elements are essential for plant growth.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.