Final answer:
The "age of reptiles" is the Mesozoic Era, which is characterized by the dominance of dinosaurs and spans from approximately 252 to 66 million years ago.
Step-by-step explanation:
The era that is known as the "age of reptiles" is the Mesozoic Era, option B). This era, which lasted from about 252 to 66 million years ago, is famous for the dominance of dinosaurs and is commonly referred to as the age of reptiles due to the prevalence and diversity of these creatures during this time. The Mesozoic Era is divided into three periods: Triassic, Jurassic, and Cretaceous. The dominance of the dinosaurs and various other reptilian species continued until the end of the Cretaceous, concluding with a massive extinction event at the Cretaceous-Tertiary boundary. The only surviving descendants of the dinosaurs today are birds, which evolved from a group of theropod dinosaurs.