Answer:
The correct answer is industrial age.
Explanation:
The starting of the industrial revolution in the mid-eighteenth century led to an enhanced application of machines to perform different kind of activities, in this the prime source of power used was the steam machines that needed burning of the coal, in order to heat water and generate steam, which later was used to fuel different kinds of engines. This burning of coal led to an increase in the levels of carbon dioxide in the air, thus, beginning the industrial age.