How do the views of the speaker's neighbor in "Mending Wall" help develop its central idea? The fact that the neighbor suggests that rebuilding the wall is foolish is what makes the speaker change his position. The neighbor's belief in the need for a wall is why the two men must go through the trouble of rebuilding this one. The fact that the neighbor blames hunters for wrecking the wall is the source of the disagreement the men have over the wall. The neighbor's insistence that good fences make good neighbors is what pushes the speaker to suggest they replace the wall with a fence.

The neighbor's belief in the need for a wall is why the two men must go through the trouble of rebuilding this one.

Explanation:

Robert Frost's poem "Mending Wall" maybe, at the literal level, about two neighbors coming together to mend their fence in between their property. But on a deeper level, it focuses on the importance and need of maintaining fences or boundaries, exploring the themes of separation, or how it can act as a glue to join neighbors.

While mending the broken and damaged fence, the speaker reveals how he doesn’t understand the need for a fence in between their properties. To this, his neighbor comments that "good fences make good neighbors". And in this remark, the speaker understands that to be on good terms with his neighbor, he needs to put aside his personal opinion and agree to the mending of the fence. And that's why the two men must go through the trouble of rebuilding their wall, as the neighbor believes in the need for a wall, which the speaker needs to follow if they are to remain good neighbors.

This act also develops the theme of how contradictory different people can be, for the wall both acts as a means to connect and separate the two men, while also maintaining the peace between them.

Thus, the correct answer is the second option.