Explanation:

A-2; B-4; C-1; D-3

Potassium bromide (KBr) is a salt, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the US. Its action is due to the bromide ion (sodium bromide is equally effective).

Potassium nitrate is a chemical compound with the chemical formula KNO. 3. . It is an ionic salt of potassium ions K+ and nitrate ions NO3−, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter

Potassium sulfate or potassium sulphate, also called sulphate of potash, arcanite, or archaically potash of sulfur, is the inorganic compound with formula K2SO4, a white water-soluble solid. It is commonly used in fertilizers, providing both potassium and sulfur.

Monopotassium phosphate is the inorganic compound with the formula KH2PO4. Together with dipotassium phosphate it is often used as a fertilizer, food additive, and buffering agent. The salt often cocrystallizes with the dipotassium salt as well as with phosphoric acid.