The correct answer is D. Cryogenian period
Explanation
The Cryogenian period (720 million years ago) is known as the period in which the first animals of the earth appeared, which were identified using fossils, these animals were multicellular organisms similar to sponges. Scientists claim that they can be ancestors of modern animals or extinct organisms of which nothing is known and that diversify into multiple forms during the Ediacaran period. So, the correct answer is D. Cryogenian period
