The correct answer is (d), Zinc Oxide.
Zinc oxide is a white, odorless, tasteless powder that is used in a variety of products, including cosmetics, sunscreen, and pharmaceuticals. It is also used in the manufacture of ceramics, glass, and rubber.
Zinc oxide is a good conductor of heat and electricity, and it is also a good absorber of ultraviolet light. These properties make it ideal for use in glazing pottery. When zinc oxide is added to a glaze, it helps to create a smooth, even surface that is resistant to chipping and cracking. It also helps to protect the pottery from the elements.
Alum, calomel, and zinc chloride are all substances that are used in other applications, but they are not used in glazing pottery. Alum is a double sulfate of aluminum and potassium that is used as a mordant in dyeing and tanning. Calomel is a mercury(II) chloride that is used as a purgative and diuretic. Zinc chloride is a zinc salt that is used as a wood preservative and a galvanizing agent.