The correct answer to this question is A. Although it is difficult, you can rub two Cool Ranch Doritos together to start a fire. All potato chips are flammable from the vegetable oil they are cooked in. They are made mostly of hydrocarbons and fat, both being highly flammable.
I wouldn't be worried about the chips catching on fire while in the bad because it would take a lot of friction and heat for them to catch fire. While these specific chips are known to catch fire because many people have tested them, I'm sure other chips can also catch fire when rubbed together.