What type of poem is characterized as an Italian sonnet comprised of an octave and sestet?

A Petrarchan sonnet is indeed characterized by its structure consisting of an octave followed by a sestet. The octave typically follows an ABBAABBA rhyme scheme, creating a problem or situation, while the sestet can vary in rhyme scheme (commonly CDCDCD or CDECDE) and serves to resolve or reflect on the theme presented in the octave. This specific division allows for a clear transition in thought and mood within the poem, which is a distinctive feature of this form.

In contrast, a Shakespearean sonnet features three quatrains followed by a final rhymed couplet, creating a different rhetorical structure and flow. A Spencerian sonnet, while also structured in quatrains, interlocks the rhyme scheme, giving it yet another distinct style. A ballad, on the other hand, is a narrative poem that often tells a story and does not conform to the structured form of sonnets; it is typically written in a series of stanzas with a refrain, focusing on narrative rather than thematic resolution.

Thus, the Petrarchan sonnet is defined by its specific octave and sestet structure, making it the correct choice.