In the final stanza of “Wilderness,” the speaker says he is the keeper of a zoo inside of himself. What does he mean?

A. He is responsible for keeping control of his inner emotions.
B. As a human, he is not subject to the passions of wild animals.
C. He has a responsibility to control and protect the natural world.
D. He is a civilized human, but like other humans he has passions and cravings.