What does prevent mean be educational about it

In figure 4 of the telephone components what do the labels lettered a to e

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

The playwright would be able to express __ but the painter likely would not