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 best fuel gas when used with oxygen is: 
Select and explain. 
A. Hydrogen, B. Natural gas, C. Propane, D. Acetylene
C: Propane
Answer: C: Propane 
Explanation: Propane
Of the fuel gases, the best choice is propane. Butane, which is more readily available in some parts of the world, has a similar flame temperature and heat content as propane. Both  propane  and  butane have the advantage of being relatively pure compounds; therefore, they are uniform in quality are virtually water-free, and burn cleanly (provided that the torch flame is properly adjusted).