What is the role of tone in poetry?
a. to provide rhythm.
b. to create images.
c. to enhance a style.
d. to express an attitude.

The role of the tone is the poetry is D. to express an attitude.
By simply changing your tone in the poetry, you can give your audience a hint what attitude you have. The tone plays a very important part of the poetry because without the presence of tone, you will not be able to express your character, it would be hard for you to tell the audience that you are a sarcastic person without using your tone as a hint.