In my opinion, the correct answer is A. celebratory. Not just because the poem begins with the famous incantation "I celebrate myself, and sing myself", but because its very purpose is the celebration of a personal and collective identity. He celebrates a nation, a universe, nature, sex, human bonds, love, pride. He celebrates himself as Walt Whitman, but also as an epitome of a human being, and an epitome of a new American spirit.