Read the passage from an argumentative essay.

Vaccines are a safe and effective way to avoid harmful diseases. The proof lies in the history books—smallpox has not been seen in the United States since 1948, or anywhere else in the world since 1977. That is because smallpox vaccines eradicated the disease from the planet. Despite the obvious effectiveness of vaccination, opponents argue that vaccines can contain harmful ingredients, such as aluminum, which, in excess, may lead to neurological damage. However, until studies show a direct and irrefutable link between vaccines and harmful outcomes due to their ingredients, we should continue to give our bodies the best chance for survival by receiving vaccinations.

Which statement best evaluates the effectiveness of the argument?