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.
NPK (10 : 26 : 26) is a complex fertilizer that contains all three major nutrients 10% Nitrogen, 26% Phosphorous, and 26% Potash which are easily and quickly available to plants. Contain Phosphorous and Potassium in a 1 : 1 ratio.
Fertilizers are labeled N, P, or K to indicate their nutrient content in terms of nitrogen (N), phosphorus (P), and potassium (K). All three are important for plant growth.