Robert Frost's poem Mending Wall explores boundaries between men to the point of unawareness and carelessness . The wall is seen as a boundary and it is seen as a mental boundary. It has a literal meaning in the poem. Frost's neighbor is "a wall" which cannot move and cannot change. Even the repairment of the wall does not make it to change. He doesn't want to change, doesn't want to understand, even there is a small disagreement between them. The correct answer is the first option.