The higher the level of certain vitamins and minerals inthe bloodstream, the better a person's lung function, as measured by the amountof air the person can expel in one second. The lung function of smokers is significantly worse, on average, thanthat of nonsmokers. Clearly, therefore,one way for smokers to improve their lung function is for them to increasetheir intake of foods that are rich in these helpful vitamins and minerals.

　　Which of the following is an assumption on which thisargument depends?

　　(A) Smokers are less likely than nonsmokers to have dietsthat are rich in vitamins and minerals.

　　(B) The lung function of smokers whose diets are rich inthose vitamins and minerals is generally better than that of nonsmokers withcomparable diets.

　　(C) People whose diets are deficient in those vitaminsand minerals do not typically have other health problems in addition todiminished lung function.

　　(D) Stopping smoking will not typically improve lungfunction more than any diet changes can.

　　(E) Smoking does not introduce into the body chemicalsthat prevent the helpful vitamins and minerals from entering the bloodstream.

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