Concept:Fertilisers are chemical sources rich in specific plant nutrients, mainly nitrogen (N), phosphorus (P), and potassium (K).Explanation:Fertilisers like urea, superphosphate, and potash provide essential nutrients for plant growth. The three primary macronutrients in fertilisers are nitrogen, phosphorus, and potassium. These are commonly labelled as N-P-K on fertiliser packets. Iron and sodium are not the major nutrients in standard fertilisers.Answer:B. nitrogen, phosphorus and potassium