Answer:
(b). To prevent groupthink by automatically opposing whatever idea any group member proposes
Explanation:
Groupthink is a situation that occurs in a group where group members settle for an idea proposed by a group member without trying to come up with better alternatives.
This sometimes happens because the group members want to preserve harmony within the group.
A member assigned the role of devil's advocate in a group has a responsibility to prevent the group members from settling for a proposed easy solution, by opposing any idea a group member proposes, so as to generate some argument and push the group to reach a better solution if possible.