Do not waste your time looking that link up I tried looking my answer up and it said it was fake.
Answer:
Whitman is among the most influential poets in the American canon, often called the father of free verse. His work was controversial in its time, particularly his poetry collection Leaves of Grass, which was described as obscene for its overt sensuality.
Know, because know is present tense as is the rest of the sentence.
I would say A, and I think you mentioned Independence, but if you didn't then it is D
