It compares music to memories, which keep it alive in the form of vibrations.
Answer: A
Explanation
The poem is a two stanza poem with 4 lines each. Its theme is memories endurance and sensation.
"Music, When Soft Voices Die (To--)
by Percy Bysshe Shelley
Music, when soft voices die, Vibrates in the memory.-- Odors, when sweet violets sicken, Live within the sense they quicken.-- Rose leaves, when the rose is dead, Are heaped for the beloved's bed-- And so thy thoughts, when thou art gone, Love itself shall slumber on."