Hmmmmmmmmmm let's see. have you tried bleach?
Your answer is tone. It is asking about the author's "attitude" toward the topic or subject. tone is <span>the general character or attitude of a place, piece of writing, situation, etc. In this case it is toward the topic or subject of the book.</span>
The correct answer is D.
The poem discusses thirteen ways of looking at a bird. Each way is different from the others. In this way, Stevens is illustrating how perspective varies from person to person and from moment to moment.
Even the same person can view a bird differently -- how he or she sees it on Monday may not be the same as how he or she sees it on Friday. Furthermore, how one person views it is different from how someone else sees it. Perspective is varied and numerous.