Scientists compared the density of goblet cells in the lungs and the density of mucus in the lungs of three groups of people: • people who do not smoke and do not have lung disease • people who smoke tobacco but do not have lung disease • people who smoke tobacco and have lung disease. The results are shown in the table. [Table showing goblet cell density and mucus density for different groups] What is indicated by these data? 1 There is a positive correlation (relationship) between density of goblet cells and density of mucus. 2 Lung disease results in an increase in goblet cell density. 3 There is an association between tobacco smoking and an increase in mucus density.

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