单选题：根据下列材料回答第题：Passage FourHave you ever been afraid to talk bac

根据下列材料回答第题： Passage Four Have you ever been afraid to talk back when you were treated unfairly? Have you ever bought something just because the salesman talked you into it? Are you afraid to ask someone for a date?
Many people are afraid to assert themselves(坚持己见)．Dr．Robert Alberti，author of Stand Up, Speak Out，and Talk Back, thinks it’s because of their lack of confidence．“Our structure of organization tends to make people distrust themselves．”says Alberti．“There’s always a‘superior’around-a parent，a teacher，a boss-who‘knows better’．These‘superiors’often gain when they keep breaking at your self-image．”
But Alberti and other scientists are doing something to help people assert themselves．They offer“assertiveness training”courses-AT for short．In the AT course people learn that they have a right to be themselves．They learn to speak out and feel good about doing so．They learn to be aggressive without hurting people．
In one way, learning to speak out is to overcome fear．A group taking an AT course will help the shy person to lose his fear．But AT uses an even stronger motive-the need to share．The shy person speaks out in the group because he wants to tell how he feels．
Whether or not you speak up for yourself depends on your self-image．If someone you face is more“important”than you，you may feel less of a person．You start to doubt your own good sense．You go by the other person’ s label．But，why should you?AT says you can get to feel good about yourself．And once you do，you can learn to speak out．People are reluctant to talk back because____． A．they have a poor self-image
B．they have not received AT courses
C．they have not grasped communication skills
D．they are not generous enough to share things