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: ENT
[{'content': 'Common cold is caused primarily by: \nSelect and explain. \nA. Viruses, B. Bacteria, C. Fungi, D. Allergy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Common cold/coryza/Acute Rhinitis is primarily caused by viruses, e.g. Adenovirus, Picorna virus, Rhinovirus, Coxsackie and ECHO viruses. Secondary Invasion by Bacteria Occurs Later.', 'role': 'assistant'}]