Answer:
"The smallpox vaccine does not contain smallpox virus and cannot spread or cause smallpox. However, the vaccine does contain another virus called vaccinia which is live in the vaccine. Because the virus is alive, it can spread to other parts of the body or to other people from the vaccine site."
[Copy and pasted from a medical website]
B is the answer because the rest of them u can get back but not coal
I would say, because not all the time does a mutation organism live to reproduce.
