The correct answer would be a. Vaccines! This is because vaccines are an important and integral part of our society! And before I say anything further because I know people like to argue it and that's okay but vaccines don't cause autism or any other similar disorder. There is no evidence for this at all. In any case, when we're injected with vaccines we're given doses of antibodies so that our bodies would be prepared for that disease, because we have already seen the same particles in our vaccine, our body will know how to react in a proper and efficient way when it sees it in a "disease-like" form!
