What lesson dose Mr. Bixby try to teach the narrator in A Cub Pilot

This question is incomplete. I've found the complete question online. It is the following:

What lesson does Mr. Bixby try to teach the narrator in “A Cub Pilot”?

A. to know when he is being tricked

B. not to be so certain of his own abilities

C. not to rely on his existing knowledge

D. to keep a cool head in tense situations

The lesson Mr. Bixby tries to teach the narrator is:

D. to keep a cool head in tense situations

Explanation:

In Mark Twain's "A Cub Pilot", Mr. Bixby shakes Samuel's confidence on purpose. He makes Samuel doubt his own abilities, second-guess himself. All Mr. Bixby does is ask Samuel if he is sure he can navigate on his own. Later on, however, he tells Samuel he shouldn't allow him (Mr. Bixby) nor anyone else to shake his faith in himself. He (Samuel) should keep a cool head in tense situations, no matter what it is that people tell him.

the krebs cycle and electron transport occur in the mitochondria, though other than that i would need to know more information.