Minor changes of HA are called A: Gene mutation B: Gene reassortment C: Antigenic shift D: Antigenic drift

Which<br/>of following can cause the great variation of influenza virus and<br/>wide epidemic: A: gene<br/>reassortment B: gene recombination C: transduction D: transformation E: conjunction

Which<br/>of following can cause the great variation of influenza virus and<br/>wide epidemic:() A: gene<br/>reassortment B: gene<br/>recombination C: transduction D: transformation E: conjunction