Sydney received a measles vaccine a few years ago. While vacationing at an amusement park, he comes into contact with the measle
s virus. Because he had previously received the measles vaccine, how will his immune system MOST LIKELY respond? A. It will NOT recognize the measles virus and won’t be able to fight it off. B. It will recognize the measles virus and be ready to fight it off. C. It will ignore the measles virus. D. It will help the measles virus to make more copies of itself.
