This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
[{'content': 'A 35-year-old female who was brought into the emergency department for a drug overdose requires insertion of a nasogastric tube and administration of activated charcoal. What are the three sites in the esophagus where one should anticipate resistance due to compression on the organ? \nSelect and explain. \nA. At the aortic arch, the cricopharyngeal constriction, and the diaphragmatic constriction, B. The cardiac constriction, the cricoid cartilage constriction, and the thoracic duct, C. The pulmonary constriction, cricothyroid con striction, and the azygos arch, D. The cardiac constriction, the azygos arch, the pulmonary trunk', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The esophagus typically has four constrictions. In the thorax the esophagus is compressed by (1) the arch of the aorta, (2) the left principal bronchus, and (3) the diaphragm. The cricopharyngeal constriction is in the neck.', 'role': 'assistant'}]