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
Oral malodor is detected by 
Select and explain. 
A. Gas chromatography, B. Gas Laser, C. Perio-tron, D. Perio-scan
A: Gas chromatography
Answer: A: Gas chromatography 
Explanation: None