A group leader's ability to encourage critical thinking can motivate their group-mates to engage their thinking skills and frontal cortex of the brain. As for the group's benefit, you will produce more thought out ideas, and ideas of higher levels of thought.
D is well worded and has more detail. id go with D.
The resolution is when they contained the wild mustangs in the corral gate and thought about when they will be able to reach forever.