Final answer:
Large domed skulls with horns and knobs in dinosaurs likely served for mating displays, territorial defense, and species recognition, according to many paleontologists, supporting both options a and c for their purpose.
Step-by-step explanation:
Many paleontologists believe that the large domed skulls of certain dinosaur species, which may have been adorned with horns and knobs, were likely used for mating displays, territorial defense, and species recognition. These features could serve as visual cues during competition or courtship, allowing dinosaurs to show off physical fitness or to establish dominance without the need for direct physical confrontation. Moreover, the distinctive horns and knobs could help members of the same species identify each other, facilitating social interactions and potentially aiding in group cohesion or mate selection.
The idea that these physical traits were used for mating and territorial purposes, as well as species recognition, suggests that such features played a significant role in the social and reproductive behaviors of these creatures. This multifunctional hypothesis encompasses both a and c options: (a) Mating and Territorial purposes and (c) Species recognition.