The chemical composition of the Plaster of Paris is:

Plaster of Paris is a white powder that is used for plastering walls, making casts for broken bones, making sculptures, and many more.

The chemical name of the plaster of Paris is Calcium sulphate hemihydrate and the chemical formula of the plaster of Paris is ${\mathrm{CaSO}}_4.\frac{1}{2}{\mathrm{H}}_2\mathrm{O}$.

It is obtained by dehydrating gypsum (${\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}$). A soft sulphate mineral called gypsum is made up of calcium sulphate dihydrate. Many people mine it. It serves as a fertiliser and is a key ingredient in various types of drywall, blackboard, and plaster. Many cultures have utilised alabaster, a mildly coloured variant of gypsum, for sculpture. As a byproduct of the hydration of anhydrite, it can also form as the mineral evaporite. Gypsum is only slightly soluble in water. Gypsum demonstrates retrograde solubility, which is not a property of many other salts. Gypsum naturally occurs in translucent, cleavable masses known as selenite and flattened frequently twinned crystals.

Hence, option C is correct.