39. How does the body react to the influenza virus? (A) It prevents further infection to other types and strains of the virus. (B) It produces immunity to the type and strain of virus that invaded it. (C) It becomes immune to types A, B, and C viruses, but not to various strains within the types. (D) After a temporary immunity, it becomes even more susceptible to the type and strain that caused the influenza.