Taking the whole poem into account, I think the correct answer must be C.
The jar is a small, common, impersonal object, but in Stevens' view, it affects the nature, depriving it of its inherent wilderness. Although it is one of a thousand, it still has the power and dominion over nature. Its meaningless existence leaves a negative trail in this world. If the jar was regarded as faceless a person living in a highly commercialized, industrialized world, and the nature as freedom, the parallel would be all the more effective.
our neighbours have a cat.
