Had University Students Complete Questionnaires in a Small Room,and Then

had university students complete questionnaires in a small room,and then had smoke pour into the room from a wall vent.Students who were working _______ tended to notice the smoke in _______.

A) in groups;less than five seconds
B) alone;less than five seconds.
C) on a challenging task;about 20 seconds
D) on a rote task;less than five seconds