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
Which of the following fuel gases is the best choice of heat source to carry out soldering process? 
Select and explain. 
A. Propane, B. Acetylene, C. Natural gas, D. Hydrogen
A: Propane
Answer: A: Propane 
Explanation: None