What characteristic is common across both odes and ballads?

The use of repetition is indeed a characteristic common across both odes and ballads. In odes, which are often lyrical and reflective, repetition can emphasize key ideas or emotions, creating a musical quality that enhances the poem's overall impact. This tool allows the writer to delve deeper into themes and encourages the reader to engage with the material on a more profound level.

Similarly, ballads, known for their narrative style, frequently employ repetition, particularly in the refrain of a stanza, which can reinforce the story's central themes or emotions and make the tale more memorable. The rhythmic pattern enhanced by repetition can also facilitate oral storytelling, which is an intrinsic aspect of the ballad tradition.

While other options, such as strict rhyme schemes or a focus on tragic themes, may be present in some instances, they do not universally define both forms. Repetition stands out as a stylistic element that transcends the individual characteristics of odes and ballads, making it the correct choice.