Akio just got over having the flu. His brother just got the flu. His parents are not worried about Akio getting it again because he built up an immunity to this flu strain.Which explains the type of immunity he built up?
A
active because he built up antibodies due to exposure to the fluB
active because his parents vaccinated him against the fluC
passive because his mother passed on the flu antibodyD
passive because he had antibodies added to his blood