Final answer:
The historical developments in ballet include the elimination of speech and song, the rise of "star" ballet dancers, and changes in costume. These developments are associated with the Romantic ballet era in the 19th century.
Step-by-step explanation:
The historical developments in ballet described include the elimination of speech and song, the rise of "star" ballet dancers, and changes in costume. These developments are associated with the A) Romantic ballet era. During the Romantic ballet era, which took place in the 19th century, ballet moved away from the classical form and embraced emotional storytelling, often featuring supernatural or fantastical themes. This era saw the emergence of famous ballet dancers such as Marie Taglioni and the transformation of ballet costumes to more flowing and exaggerated designs.