Final answer:
Sexual dimorphism, which refers to clear differences between the sexes of a species, may have characterized (Option A) dromaeosaurids, a group of feathered theropod dinosaurs from the Mesozoic era.
Step-by-step explanation:
Marked sexual dimorphism may have characterized dromaeosaurids. Sexual dimorphism is a distinct difference in size or appearance between the sexes of an animal in addition to difference between the sexual organs themselves. Dromaeosaurids, known as raptors, were small to medium-sized feathered carnivores that belonged to a group of theropod dinosaurs during the Mesozoic era. Evidence for sexual dimorphism within this group, while still debated, has been suggested based on differing sizes, shapes, and adornments found in fossils that could imply differences between males and females.