Is there a rule of thumb about when it's okay to consider common sense outside information and when it's not? For example, in PT132.S4.Q17, wrong answer choice (E) cites smoking as an explanation for cancer/heart disease even though the stimulus didn't mention smoking. However, in other questions (that I can't think of to link) answer choices with external information were written off. Would appreciate any insight, it's really starting to trip me up...