Final answer:
The period between 542 and 488 million years ago is known as the Cambrian period, which is option d) Cambrian.
Step-by-step explanation:
The time between 542–488 million years ago marks the Cambrian period, which is the first period in the Paleozoic era that came after the Precambrian eon and before the Ordovician period. This geological time period is known for the 'Cambrian Explosion,' a time of rapid evolutionary development where many major groups of organisms first appear in the fossil record. The correct answer to the question is option d) Cambrian.
The Ordovician Period was the second period of the Paleozoic era and occurred between the Cambrian and Silurian periods. During this period, the oceans became filled with invertebrates, the first fish evolved, and plants colonized the land for the first time.
The Cambrian is known as the first period in the Paleozoic era, following the Precambrian eon and preceding the Ordovician period. It lasted from approximately 541 to 485 million years ago. During the Cambrian Period, there was a significant explosion of new organisms. Many types of primitive animals, including sponges and small ocean invertebrates like trilobites, became abundant during this time.