Answer: A) He is annoyed that his neighbor insists on maintaining an unnecessary wall.
Step-by-step explanation: The tone of a text or sentence is the author's or speaker's attitude towards the audience, the subject or even the characters of the text. There are many different kinds of tones, like: positive, negative, objective, sad, angry, etc. In the given excerpt from "Mending Wall" by Robert Frost, we can see that the speaker is annoyed that his neighbor insists on maintaining an unnecessary wall, because he says that he only has apple trees and his neighbor only has pines (they have no animals).