The division of earth’s history into smaller units makes up the a. eras c. periods b. geologic time scale d. sequence of events

That is incorrect, the correct answer would be B.

Option B.

Explanation:

The geological time scale is a calendar of the geological history of the Earth.  Geological time refers to the time that has elapsed from the moment the earth formed until today.

This scale is divided into four geological periods: eons, eras, periods and epochs. Thanks to it, they can assign time and dates to the most important events on Earth. Inside the rocks is where more information is found about what has happened on our planet over these 4.5 billion years.

Then,

The division of Earth's history into smaller units makes up the Geologic time scale.