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': 'All of the following are true regarding influenza except- \nSelect and explain. \nA. Point mutations in hemagglutinin gene cause antigenic drift, B. Acquisition of completely new hemagglutin in gene cause antigenic shift, C. Amantidine is active against influenza B only, D. Amantidine Shortnes the illness', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]