The correct answer is A. The purpuse of this soliloquy is to help the audience understand Romeo's feelings for Juliet. At the beginning of the play Romeo is supposedly in love with Rosaline, which he expresses by means of a sonnet in the Petrarchan mode. However, after meeting Juliet he completely forgets about Rosaline, and changes both his feelings and his language. He becomes much more direct and forceful in his expression. This soliloquy is meant not only to show the audience his new feelings for Juliet, but to mark a contrast with his former, less intense, feelings for Rosaline. He has not changed one infatuation for another, but rather moved from false, melancholic love to true, vigorous love.