Carbon ^^ is the answer if I’m not mistakenn
The answer is T, True. Secondary pollutants are pollutants that we do not directly release, but that are created as a side effect of releasing primary pollutants, such as carbon dioxide, sulfur oxides, and particles such as ash and dust. Secondary pollutants include acid rain, ozone, smog, and CFC's (chlorofluorocarbons).
The expression or comment "Brain Freeze" means that the roof of your mouth is getting so cold that its affecting some of the nerves in your brain making it feel like a brain freeze.