Explanining B

Never mind I figured it out! The fact that the kids who are immune compromised are getting sick with the OPV strengthens (not weakens) the conclusion that they should switch to IPV.

Hi Abigail, I think you're exactly right- although we may not be able to go as far as to say that B strengthens. While the kids being immunocompromised might make it worse if they get polio- we don't know anything about the nature of their immune disorders. It may strengthen, or it might be immaterial Either way, A clearly weakens the argument. Since switching would lead to new natural cases of polio, these new natural cases might completely offset, or even lead to a net increase in polio cases per year.