Kirk is wearing a costume and is out with a group of friends on Halloween. Although Kirk is not ...

Kirk is wearing a costume and is out with a group of friends on Halloween. Although Kirk is not usually a mean or aggressive person, he agrees to throw eggs at passing cars and steal candy from little kids who are trick-or-treating. Which statement best explains Kirk's behavior in this situation?
 
  a. Kirk's friends are providing a descriptive norm for behavior.
  b. Because he is in a crowd, he is experiencing deindividuation.
  c. Because other people are around, social facilitation is occurring.
  d. Kirk has privately accepted that this is how people normally behave.