A nurse is teaching a client about the purpose of checking vaccine titers. Which client statement indicates an understanding of the teaching?

"A titer tells the provider whether I am currently contagious with a disease."

"A titer determines exactly how much vaccine I should get for a booster."

"A titer is only needed when someone has an allergic reaction to vaccines."

"A titer will show if my body did not respond to a vaccine and I need it again."