Concept:A sonnet with a final couplet is the English or Shakespearean sonnet form.Explanation:The English sonnet has 14 lines arranged as three quatrains followed by one couplet.Each quatrain has four lines, and the final couplet has two rhyming lines.Its rhyme scheme is ababcdcdefefgg.So the final couplet appears only when the poem contains three quatrains.In contrast, an Italian sonnet uses an octave and a sestet, without a final couplet.Answer:D. Three quatrains