Pick the odd item

The odd item is "metaphor". This is because an "elergy", "ballad", and "ode" are all types of poetry or musical forms, while "metaphor" is a literary device used in poetry and prose to make a comparison between two unlike things without using "like" or "as". Therefore, "metaphor" doesn't fit in the category of poetry or musical forms, and is the odd one out among the given options.