The clinic clients respond negatively to the need for a yearly flu shot. They ask why the medical communities don't just create one shot that will last for several years. What is the best response from the nurse?

"The shots last only for 3-6 months and must be renewed on a yearly basis."

"There is more than one strain of the flu virus, and you must be protected from all of them."

"Genetic changes make the flu virus resistant to the flu shot from year to year and different strains of the flu virus are more prevalent in different years."

"Genetic changes in the bacteria that cause the flu require a rotating course of antibiotics.