I think the correct answer from the choices listed above is option B. The theme that is emphasized in the excerpt from "Ode on a Grecian Urn" by John Keats is that the <span>unfulfilled desires and dreams seem sweeter. It is can be seen from the lines:
</span>Heard melodies are sweet, but those unheard Are sweeter; therefore, ye soft pipes, play on; <span>Not to the sensual ear, but, more endear'd,</span>
