Final answer:
The true statement regarding groups is that exposing members to others' ideas during brainstorming can decrease performance, often due to groupthink and group polarization.
Step-by-step explanation:
The correct statement about groups is that when brainstorming, exposing members to the ideas of others can decrease performance. This phenomenon can occur due to social pressures and the desire to conform leading to groupthink, where the desire for harmony or conformity results in an irrational decision-making outcome. It can also be attributed to group polarization, which is the tendency of group members to shift to more extreme positions after group discussion. Additionally, research such as Asch's conformity experiments suggest that individuals are more likely to maintain their own opinion if they have allies within the group and the collective action problems suggest decision-making and behavior monitoring is more effective in smaller, cohesive groups.