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
Sublimation is the conversion of a: 
Select and explain. 
A. Solid directly to gas, B. Gas to liquid and then to solid, C. Gas directly to liquid, D. Solid to liquid and then to gas
A: Solid directly to gas
Answer: A: Solid directly to gas 
Explanation: It is possible for some solids to change directly to a vapor by a process called sublimation as seen in dry ice; this, however, has no practical importance as far as dental materials are concerned.
Sublimation is the conversion of a solid directly to gas.
Reference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 18