Which characteristic is essential to a sonnet?

A sonnet is defined by its precise structure, which includes a specific length of 14 lines and a distinct rhyme scheme. This format is fundamental to the identity of a sonnet and is what differentiates it from other types of poetry. The traditional forms of sonnets, such as the Shakespearean (or English) sonnet and the Petrarchan (or Italian) sonnet, adhere to unique rhyme patterns and meter, typically iambic pentameter.

The characteristic of having 14 lines is non-negotiable; any variation in the number of lines disqualifies the poem from being classified as a sonnet. The specific rhyme scheme associated with each type of sonnet contributes significantly to its musical quality and thematic development. This structure allows poets to craft tightly woven arguments or emotional expressions within the limited framework, showcasing their skill in manipulating language and form.

Other options touch upon elements that may enhance a sonnet but are not essential to its definition, such as imagery or narrative perspective. These features can certainly enrich a sonnet but do not constitute the defining characteristics that classify it as a sonnet.