The earliest known complex,multicellular life forms originated toward the end of the
A) Archean Eon.
B) Proterozoic Eon.
C) Paleozoic Era.
D) Cenozoic Era.

Question

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The earliest known complex, multicellular life forms (such as early sponges) originated towards the end of the Proterozoic Eon, around 600 million years ago. The Archean Eon and the early part of the Proterozoic Eon were dominated by simple, single-celled organisms. The Paleozoic Era, which began around 542 million years ago, saw the rise of more advanced forms of life, including fish, amphibians, and reptiles. The Cenozoic Era, which began around 66 million years ago, is characterized by the evolution of mammals, birds, and flowering plants.

The Earliest Known Complex,multicellular Life Forms Originated Toward the End