What causes the setting process of plaster of Paris (POP)?

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Variation in solubility between CaSO4·½H2O and CaSO4·2H2OChemical interaction of CaSO4·2H2O with waterFormation and expansion of CaSO4·½H2O crystal nucleiReaction occurring between hemihydrate and dihydrate formsNone of the above

Explanation

The setting of plaster of Paris is primarily due to the difference in solubility between calcium sulfate hemihydrate (CaSO4·½H2O) and calcium sulfate dihydrate (CaSO4·2H2O), which drives the transformation and hardening process.