The correct option is C Mesozoic
The total span of Earth’s evolution or geological time is basically divided into six eras - Azoic, archaeozoic, proterozoic, palaeozoic, mesozoic and cenozoic. Mesozoic era is known as "the golden age of reptiles" as it was marked with the emergence and evolution of a variety of reptilian species. This era witnessed the dominance of dinosaurs and toothed birds like Archaeopteryx, evolution of marsupials from prototheria etc. Cenozoic era is the era in which we are currently living, and it is called the "age of mammals".