Research on the effects of movie watching on teens' smoking behavior (i.e., watching popular movies containing instances of smoking) found that ____

a. there were only very weak effects
b. there were moderately strong effects—but these effects disappeared when one accounted for individual differences on personality variables
c. there were moderately strong effects—but these effects disappeared when one accounted for parental smoking and peer group smoking
d. there were progressively stronger effects as the exposure to instances of smoking in movies increased

D