Answer:
D. "Love."
Step-by-step explanation:
John Keats's "Ode on a Grecian Urn" is a recollection of when the poet addresses an ancient Grecian Urn. The lines in the question are from the second stanza of the poem.
This ancient item has a picture of a young man and his lover, him playing a pipe and she lying under a tree. Keats exclaims that the unheard melodies that he is playing are much sweeter than anything else as they are unaffected by time. The young man may not be able to kiss his love but he should not worry for they are already engraved in the picture which will forever stay. They are frozen in time, with their beauty intact and their love will last forever no matter how time goes.