Final answer:
Groupthink occurs in cohesive groups and has led to decision-making failures like the Challenger disaster (a). It happens when group harmony overrides sound decision-making and can be countered by open discussion and considering all viewpoints.
Step-by-step explanation:
The phenomenon that occurs most often in highly cohesive groups and when the group is confident concerning their course of action early in the process, and which has been interpreted to having resulted in the Challenger space shuttle disaster, is groupthink.
Groupthink is a situation where the desire for group consensus overrides the necessity of considering realistic alternatives and often leads to irrational decision-making. Cohesiveness, directive leadership, and isolation from external viewpoints are some of the identifiable causes of groupthink.
To avoid groupthink, strategies such as seeking outside opinions, private voting, withholding leaders' opinions until all group members have participated, and thoroughly researching all viewpoints can be employed.