ANS:A - mixed

NPK refers to a mixed fertiliser. Explanation:

1. Composition: NPK fertilisers are named after the three main nutrients they contain: nitrogen (N), phosphorus (P), and potassium (K). These fertilisers are formulated to provide a balanced combination of these essential nutrients to support plant growth and development.
2. Importance of Balanced Nutrients: Nitrogen is essential for leafy green growth, phosphorus promotes root development and flowering, while potassium enhances overall plant health, including disease resistance and stress tolerance.
3. Formulation: NPK fertilisers come in various formulations and ratios of nitrogen, phosphorus, and potassium, tailored to specific crop needs and soil conditions. These fertilisers may be in solid forms such as granules, powders, or pellets.
4. Usage: NPK fertilisers are widely used in agriculture to replenish soil nutrients and improve crop yields. They are applied to the soil or as foliar sprays to provide plants with the essential elements required for optimal growth.