Strayer and Johnston (2001) Investigated the Effects of Attention on Driving

Strayer and Johnston (2001) investigated the effects of attention on driving performance. In the first task, the driver had to listen to a list of words over the phone and repeat or shadow them back. In the second task, the driver had to listen to a list of words over the phone and had to say a word beginning with the last letter of the word just heard. The results of the study showed that:

A) shadowing words did not impair driving performance.
B) neither shadowing words nor generating words impaired driving performance.
C) shadowing words impaired driving performance significantly more than generating words.
D) generating words impaired performance significantly more than the simple shadowing task.