Read the passage. (1) Ask young people today if they know of anyone who has had smallpox, and they might ask, "What's smallpox?" (2) That is because this disease was eradicated from the planet decades ago thanks to vaccinations. (3) Despite the obvious effectiveness of vaccination, opponents of this procedure argue that humans are better off fighting diseases on their own without adding anything potentially harmful to their bodies. (4) Still, the American Academy of Pediatrics says that vaccines can be 99 percent effective and the Centers for Disease Control claims that, over a 10-year period, vaccines allowed 322 million children to avoid illnesses. (5) So the next time someone tells you that vaccines are poisoned apples that will lead to a fate like Snow White's, counter their argument with the facts. (6) The bottom line is that vaccines are safe to use and save lives. Which sentence in the passage contains an allusion? sentence 1 sentence 3 sentence 4 sentence 5