When Derek joined her , the door man unhooked the rope to let them through , still watching Lucy with undisguised lust as they walked in . A look of utter confusion shown on Derek 's features as they were granted entrance into the club . He draped an arm over Lucy 's shoulders and they made their way through the crowds of people . " So how 'd you do that ?

Based on the preceding passage, choose your answer for question What may be the reason for Derek 's confusion ?
Options are:
[1]. He did n't understand how they were able to get in so fast .;
[2]. He did n't understand why he was let in with her .;
[3]. He did n't understand why they were there .;
[4]. He did n't understand why he bothered coming .;
The answer is:
[1].