How does the setting of "mending wall" develop its central idea?

a. the rural setting pits the speaker, who is from the area, against his neighbor, who has recently arrived from the city.

b. the isolated setting one reason the speaker begins to wonder whether he and his neighbor needs walls to separate their well-defined properties.

c. the interior setting makes the speaker feel as though the walls of his home are barriers that are keeping him from a friendship with his neighbor.

d. the modern setting is what makes the speaker want to rebuild the old walls that have crumbled along the border of his property.