Correct Answer: (d) Calcium Sulphate
Note: Calcium sulfate (gypsum) is an important agriculturally useful compound, which is used with fertilizers. Plants get both calcium and sulfur, important elements, through calcium sulfate. Calcium stimulates the growth of root hairs. Due to the lack of this element, chlorophyll does not work properly. Sulfur helps in the development of roots. In the absence of this element, the leaves start turning yellow and the size of the leaves decreases, and the plants remain dwarf.