Could someone explain what AP Science is? And how it's different to regular science?
In any case, I'd say none of them. I would personally look into farming-based sciences, because let's face it. Nature is still going to thrive, no matter what most post-apocalyptic fiction says. The only way you're going to have the nuclear wasteland is if the world is wiped clean by cobalt bombs. And if that happens, no one is surviving the apocalypse, considering that the result would be extremely radioactive and with a half-life of 5.27 years.