To apply NPK, an NP complex has to be supplemented with

Answer: Option B

To apply NPK, an NP complex has to be supplemented with Potash (Potassium-K).
NPK is a complex fertilizer consisting of Nitrogen, Phosphorus and Potassium. Each of these fundamental nutrients plays a key role in plant nutrition. Plant cells use these nutrients to grow and develop. They help root and shoot development, flower and fruit formation and assist natural pest and disease resistance.