Which is an example of active immunity?
1) antibodies produced from a vaccine, or a person receiving an injection of antibodies
2) a fetus acquiring antibodies through the placenta, or a person receiving an injection of antibodies
3) a person receiving an injection of antibodies, antibodies produced when the flu strikes
4) antibodies produced from a vaccine, antibodies produced when the flu strikes
5) a fetus acquiring antibodies through the placenta, antibodies produced when the flu strikes