Need clear work please with explanation thank you... You want to be nice , so you galdly hold the door for the person behind you that is also coming

Need clear work please with explanation thank you...

You want to be nice , so you galdly hold the door for the person behind you that is also coming into your secure office building this is an example of

a) careleness with one's office.

b) tailgating

c) Extortion

d) shoulder surfing.