Anybody play smash Ultimate? but here's a riddle for fun. I speak without a mouth and hear without ears. I have no body, but I come alive with wind. What am I? 

How can you avoid the problem of groupthink? a. by choosing a group leader to direct the group b. by composing the team of only like-minded individuals c. by encouraging all members to voice their opinions d. by keeping quiet when you disagree with another group member's opinion