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
All of the following are true regarding influenza except- 
Select and explain. 
A. 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
C: Amantidine is active against influenza B only
Answer: C: Amantidine is active against influenza B only 
Explanation: None