How do you know that a group in which you're taking part is suffering from groupthink? the group would rather take the time to come to the right decision rather than agree too quickly on what may be the wrong decision. peer pressure makes you agree with the ideas of the other people in your group. minority dissent is allowed, even encouraged. the group actively considers new ideas, even if these ideas challenge underlying assumptions. all ideas and conclusions must be backed up with data.

the answer is:  Peer pressure makes you agree with the ideas of the other people in your group.

A group think occurs when several parts of group members decided to conform to a certain idea or principle because they do not want to disrupt the harmony of the group, even though they personally rejected the idea or principle.

Under such situation, peer pressure plays a crucial role. Challenging the idea held by a large portion of the group could make disagreeing members being discarded by the group. Because they do not want this outcome, the peer pressure makes them agree with the group's idea.