Final answer:
By the Triassic period, the supercontinent Pangaea split into Laurasia and Gondwanaland. Later, these would give rise to the current continents, with Pangea leading to Gondwanaland, but not individual continents like Asia or North America at that time.
Step-by-step explanation:
During the Triassic period, the giant supercontinent known as Pangaea began to rift and split into smaller continents. By the end of the Triassic, Pangaea was primarily divided into two large landmasses: Laurasia, which would eventually become today's Northern Hemisphere continents including North America and parts of Asia, and Gondwanaland, which would later split further to form the continents in today's Southern Hemisphere. Therefore, the correct answers to which continents emerged from the supercontinent during the Triassic period are B. Pangea and D. Gondwanaland, as Asia and North America as separate continents evolved at a later stage.