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
[{'content': 'Which of the following is the gold standard for testing breath matador (halitosis)? \nSelect and explain. \nA. portable volatile sulfide monitor, B. self examination, C. gas chromatography, D. organoleptic rating by a judge', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]