Energy Return on Energy Investment is____.
O the total amount of energy that we can extract from a source without having to invest any energy to do so .
O the total amount of energy we can extract from a source plus the total amount of energy needed to obtain, produce, and ship energy from the source.
O the difference between the amount of energy we can extract from a source and the amount of energy required to obtain, produce, and ship energy from the source.
O the ratio of the amount of energy we can extract from a source compared to the energy we must spend to obtain, process, and ship energy from the source.