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
The main difference between dental stone and dental plaster is: 
Select and explain. 
A. Chemical composition, B. Self life, C. Shape and size of particles, D. Solubility in water
C: Shape and size of particles
Answer: C: Shape and size of particles 
Explanation: None