Personal narratives are most beneficial to which type of persuasive speech

It would be most beneficial for a value speech.

What happens to the influenza virus every 20-40 years and why?

Immunization is the introduction of a foreign substance to provoke  the immune response system.  immunizations are the same as vaccinations. it introduces foreign (but dead/ weakened) illnesses to train the body to fight against them. specific viruses and bacteria have specific antigens, antigens act sort of like name tags. these name tags the immune system recognize what's dangerous to the body and what's safe.