<span>Edward Jenner discovered a vaccination against [smallpox] by infecting a boy with [cowpox]. He noticed that milkmaids who got cowpox never got smallpox and developed his theory from there. He is the father of the study of immunity and immunisation.</span>
I would say all of the above, because all of those seem to be true
-hope it helps :3
What are the options they are giving you?
Overwhitened eventually become semitransparent and start to develop a blue-gray tint!
