In what way was ralph waldo emerson important in henry david thoreau's professional life?

a. emerson criticized thoreau's work, which led to a long-standing rivalry.
b. emerson was the one who paid thoreau's poll tax, which freed him from prison.
c. thoreau could not find a publisher for his books and relied on emerson's influence.
d. thoreau lived on emerson's land, which was the subject of one of his books.