Concept:NPK values show the relative amounts of nitrogen, phosphorus, and potassium in a fertilizer.Explanation:In NPK 5−10−15, the nutrient parts are nitrogen =5, phosphorus =10, and potassium =15.Simplify the ratio by dividing each term by the common factor 5.5:10:15=1:2:3.Answer:The nutrient ratio is 1:2:3, which is option B.