The correct answer is (d), rock phosphate. Rock phosphate is a mineral that is used as a major fertilizer. It is a major source of phosphorus, which is an essential nutrient for plant growth. Phosphorus is used by plants to build cell walls, DNA, and other important molecules. Rock phosphate is also a source of calcium and other minerals.
Sulfur is not a major fertilizer. It is a micronutrient that is needed by plants in small amounts. Sulfur is used by plants to build proteins and other important molecules.
Gypsum is a mineral that is used as a soil amendment. It can help to improve the drainage and fertility of soil. Gypsum is also used to make plaster and other building materials.
Potash is a mineral that is used as a fertilizer. It is a major source of potassium, which is an essential nutrient for plant growth. Potassium is used by plants to regulate water balance, build proteins, and produce energy.