What structural feature is characteristic of a sonnet?

A sonnet is defined by its specific structural features, notably its form of fourteen lines. Each line traditionally contains ten syllables, following the iambic pentameter, which creates a rhythmic consistency throughout the poem. This strict structure contributes to the sonnet's ability to convey profound themes and emotions within a limited form, making it a unique and impactful poetic style.

The first choice refers to a rhyme scheme of different lengths, which does not apply to sonnets, as they traditionally follow specific patterns, such as the Petrarchan (abbaabba) or Shakespearean (ababcdcd) schemes. The third option mentions a free verse format, which is characterized by a lack of consistent rhyme and meter, directly opposing the structured nature of a sonnet. Lastly, the fourth choice speaks of alternating stanza lengths, which is not typical in sonnets since they consist of a uniform arrangement of fourteen lines without variations in stanza length.