Final answer:
Reptiles, specifically dinosaurs, were the dominant forms of life during the Mesozoic Era, which is known as the Age of Reptiles. Therefore , the correct answer options is b)
Step-by-step explanation:
The dominant forms of life during the Mesozoic Era were reptiles, specifically dinosaurs. This era, often referred to as the "Age of Reptiles," saw a diverse array of dinosaur species flourish on land, in the seas, and in the air. The Mesozoic was comprised of three periods: Triassic, Jurassic, and Cretaceous.
Dinosaurs became so dominant during this era that it wasn't until a catastrophic event at the end of the Cretaceous period, likely a combination of meteor impact and volcanic activity, that their dominance ended. This event paved the way for mammals to become the dominant life form in the subsequent Cenozoic Era, an era that witnessed the rise and diversification of mammals, birds, and flowering plants.