"It addresses the effects of racism and oppression in society" is the best which describes the reason why "Sympathy" is a naturalist poem. Literary naturalism emphasizes observation and the scientific method in the fictional portrayal of reality.
Other characteristics of literary naturalism are:
- detachment: the author maintains an impersonal tone and disinterested point of view
- determinism: the opposite of free will, in which a character's fate has been decided, even predetermined, by impersonal forces of nature beyond human control
- a sense that the universe itself is indifferent to human life