Question

in ancient times which was the most common source of heat energy?
= in ancient times wood was the most common source of heat energy.

Answer 1

The Question has the answer itself.

Answer 2

Answer↓↓↓

The most common source of biomass is wood.

Explanation↓↓↓

Biomass is a form of renewable energy that derives from living, or recently living organisms. The most common source of biomass is wood. Wood has been used since the ancient times, mostly to produce fire.

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