There are multiple ways you can become immune to a virus. You can contract the virus and survive and get treated, what that will do is put a vaccine into your immune system so your white blood cells can fight back, a vaccine basically does this but instead the virus is dead. Also human evolution can cause immunity.
The answer is A, do you want me to explain it? It’s pretty simple, you just need to follow all the signs in brackets and match them in those in the answer
