Final answer:
Horsetails belong to the Eukarya domain and the Plantae kingdom.
Step-by-step explanation:
Horsetails fall under the domain Eukarya and the kingdom Plantae.
Horsetails have multicellular structures with membrane-bound organelles and cell walls that contain cellulose, which are characteristics of eukaryotic plants. They also have the ability to perform photosynthesis, further classifying them as plants.