Answer:
The correct answer is Eons.
Step-by-step explanation:
The largest formal unit of geologic time is an Eon.
An Eon is a very long period of time for which we cannot know exactly how many years it represents.
For geology, the Eon represents a period of a billion years, but also, it is each one of the periods in which the geological time of our planet is divided.
Therefore we have the following Eons:
-Phanerozoic: 543 million years ago.
-Proterozoic : from 2,500 to 543 million years ago
- Archaic: from 3,800 to 2,500 million years ago.