This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Plaster of paris: 
Select and explain. 
A. Is wet calcined hemihydrate, B. Has porous and irregular crystals, C. Is α— hemihydrate, D. Has a W / P of 0.2
B: Has porous and irregular crystals
Answer: B: Has porous and irregular crystals 
Explanation: None