In the Spilich Et Al

In the Spilich et al. study of the effects of smoking that was discussed in the text, active smokers were found to do better than nonsmokers on a driving task but did worse than nonsmokers on a cognitive task. However, over all three tasks (the third was pattern recognition and the groups were not different on that) active smokers did not differ from nonsmokers on performance. The results suggest

A) an interaction between smoke group and task, and a main effect for smoke group.
B) an interaction between smoke group and task, but no main effect for smoke group.
C) a main effect for smoke group, but no interaction between smoke group and task.
D) a main effect for task only.