@jj the study says that smokers who just smoked a cigarette have better short-term memory than non smokers, regardless of whether the nonsmoker just had a cigarette.
We're looking for which of the statements can't be true - that is, all the others could be true.
A) Could be true. The difference between non smokers who had or had not just smoked a cigarette are unaddressed by the prompt, so it could be true.
B) Cannot be true. The prompt tells us smokers have better short term memories overall, so this is disproven by the prompt.
C) Could be true. We know that smokers' memory skills are affected for 8 hours, but we don't have information beyond that.
D) Could be true. This is very specific and not addressed by the prompt. We know some of the overall trends, but not the case of each individual.
E) Could be true. The prompt doesn't tell us how the short term memory strengthens or fades during the time after the cigarette, so this is unaddressed.
