Which aspect of the following poem might imagists most admire?
the footsteps of the cat upon the snow:
plum-blossoms.
a. the overlapping images of a cat’s footprints and flowers
b. the contrasting images of a cat and snow
c. the use of punctuation
d. the reference to nature and animals
e. the related images of footprints and freshly fallen snow
i know that it is not c, just not sure of the answer.

Imagists believed that poems should have "no ideas but in things." In other words, they would described powerful images, and instead of explaining what those images meant, they would let the reader decide what the meaning or value of those images might be. 

Imagists were especially fond of inviting the reader to recognize how very different sorts of images can actually be really similar. Ezra Pound famously did this with his short poem "In a Station of the Metro," which associates "faces in the crowd" with "petals on a wet, black bough."

The poem in your question does something very similar by associating the cat's footprints in the snow with the blossoming flowers of a plum tree. The writer wants you to recognize the odd visual similarity of the footprints and the flowers, ideally to show how there's a kind of cosmic connectedness in the world by (because two very different things end up being really similar).

That's why I think your best answer is A.