Which poetic form consists of four lines, typically with a specific rhyme scheme?

The correct choice is indeed the heroic quatrain, which is a poetic form characterized by its four-line structure and specific rhyme scheme, typically ABAB or AABB. This form often employs iambic pentameter, which gives it a rhythmic quality that complements its thematic elements. The heroic quatrain is frequently used in English poetry, especially in narratives and epics, where it can convey a sense of grandeur or heroism.

In contrast, a sestet is a six-line stanza, making it too long to fit the definition of four lines. A couplet contains only two lines, and while it does have a rhyme scheme, it does not fulfill the requirement of having four lines. Finally, the term stanza refers to any grouped lines in a poem, which can vary in number and structure, so it does not specifically denote the four-line form that the heroic quatrain represents.