Answer:
A. Early signs of life on earth
Step-by-step explanation:
The Hadean, before the Archean, is the first geologic eon of Earth. It began with the formation of the Earth about 4600 million years ago and ended 4,000 million years ago. The planet had just formed and was still very hot due to high volcanism, a partially molten surface. Some geologists labels the period before the earliest-known rocks on Earth. At the end of it much cooler surface temperature and the formation of solid rock enabled to flaurish the life.