Which one of the following is correct?
The setting of the plaster of Paris is the process of

Correct option is C

The correct answer is (c) hydration to yield another hydrate
Plaster of Paris (POP) is chemically known as calcium sulfate hemihydrate (CaSO4⋅1/2H2O).​
When mixed with water, it undergoes a hydration process to form calcium sulfate dihydrate (gypsum) (CaSO4⋅2H2O).

Chemical Reaction:

This reaction releases heat (exothermic) and causes the plaster to set into a hard mass.

Additional Information:

• Dehydration: Dehydration is the removal of water, which occurs during the preparation of Plaster of Paris from gypsum, not during its setting.
• Oxidation with atmospheric oxygen: There is no reaction involving oxygen during the setting of Plaster of Paris.
• Combination with atmosphere: The setting process does not involve atmospheric components like oxygen or carbon dioxide.