What literary device is used in these lines from \"music, when soft voices die (" by percy shelley? .
odors, when sweet violets sicken. live within the sense they quicken..
metaphor.
alliteration.
allusion.
apostrophe

I too believe the answer to be letter B) alliteration.

Explanation:

The lines we must analyze are:

"Odors, when sweet violets sicken,

Live within the sense they quicken."

By defining each of the devices provided in the question, we can choose the one that applies to those lines. A metaphor is comparison between two different things stated without the help of support words ("like" or "as"). A metaphor claims that "thing A is thing B", for example: your eyes are stars. In the lines above, we do not have a metaphor. There is no comparison being made.

Alliteration is a literary device in which sounds or letters at the beginning of words that are close to each other in a structure are repeated. Such repetition creates mood and rhythm. That is precisely what we have in the lines above. The letter s is repeat in three close words:

"Odors, when sweet violets sicken,

Live within the sense they quicken."

An allusion is a figure of speech in which a reference is made to something or someone, but in an indirect manner. For instance: you are more beautiful than Aphrodite - that's an allusion to a Greek mythology figure. The author does not explain who Aphrodite is, he simply mentions her trusting the audience will grasp the reason why she was mentioned. We do not have an allusion in Shelley's lines.

Apostrophe is a figure of speech in which the author of a poem speaks directly to someone who is not there, someone who is dead, or an inanimate object. As we can note, that does not happen in the lines we are studying. If the speaker had been talking to the odors instead of about them, then we would have an apostrophe.