Final answer:
Stegosaurs and ankylosaurs are united in the group called C. Thyreophora, which is a category of armored dinosaurs within the larger clade Ornithischia, the 'bird-hipped' dinosaurs.
Step-by-step explanation:
Stegosaurs and ankylosaurs are united in a group called Thyreophora. This group is known for dinosaurs that were armored with bony plates or spikes and include both the stegosaurs, with their distinctive rows of plate structures along the back, and the ankylosaurs, recognized for their heavy armor and club-like tails. Their shared characteristics, such as the development of body armor, place them together within this particular group of dinosaurs. The Thyreophora subgroup is one of the main classifications within the wider clade of Ornithischia, often referred to as the "bird-hipped" dinosaurs due to their pelvic structure, although it's important to note that modern birds actually evolved from the saurischian dinosaurs with "lizard hips".
Stegosaurs and ankylosaurs are united in a group called Thyreophora. Thyreophora is a suborder of dinosaurs that includes armored dinosaurs like stegosaurs and ankylosaurs. These dinosaurs had defensive adaptations such as bony plates or spikes on their bodies to protect themselves from predators.