Answer:
A. Isolated from dissenting viewpoints
Step-by-step explanation:
Groupthink is to change the views of group leaders to comply with what they feel is the consensus of the group, the exclusion of diverse viewpoints leads to the group's failing decision.
Christopher as the directive leader of a student group, When discussing important policy decisions, this group will be at greatest risk for groupthink if it is also isolated from dissenting viewpoints
If the group is isolated from hearing alternative or new viewpoints, groupthink may be more likely.