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: Medicine
[{'content': 'Which of the following cardiovascular conditions can result in a medical emergency in the dental office causing\nsubsternal pain, facial pallor, and cold perspiration: \nSelect and explain. \nA. Angina pectoris, B. Congestive heart failure, C. Hypertension, D. Patent ductus arteriosus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]