Answer:
It depends on the optimum dosage of NPK.
Step-by-step explanation:
The farmer gain more productivity from that type of fertilizer which have optimum dosage of nitrogen, phosphorus and potassium fertilizers because these three fertilizer needed by the plant in large quantity and having great contribution in the yield of plant so if ''fertilizer a'' has optimum dosage of these three nutrients so we can say that ''fertilizer a'' produces more food as compared to no fertilizer and ''fertilizer b'' whereas if ''fertilizer b'' has optimum dosage of these nutrients so ''fertilizer b'' produces more food.