Final answer:
Robert Frost's 'Mending Wall' suggests his stance as an opponent of building walls due to the thematic elements and narrative voice in the poem.
Step-by-step explanation:
Robert Frost's poem 'Mending Wall' deals with the themes of boundaries and the relationships between neighbors. Considering the line from the poem, 'Something there is that doesn't love a wall,' it can be argued that Frost leans toward being an opponent of building walls. This line reflects the natural forces that continually destroy the wall, requiring it to be mended. The speaker in the poem also questions the necessity of the wall, suggesting a philosophical opposition to barriers. On the other hand, his neighbour upholds the old adage 'Good fences make good neighbours,' presenting a case for the proponent side. Despite this counterpoint, the poem as a whole and through its narrative voice seems to extend a more critical view on the concept of walls that divide.
The correct answer in the context of the poem would be: a) Opponent