How does Twain show the importance of “cool, calm courage that no peril can shake” in a riverboat pilot?

Answer:
Option-(C): He recounts how he was courageous in navigating around the bend above the island 66.
Explanation:
As Mark Twain faces some difficult times while he is leading his boat along with his crew in it but he is a very courageous man who did not hesitate from navigated the right path to travel.