Fact 1: Energy is used for heating a building by a heating system. Fact 2: Radiators are used to heat the building, The energy source is oil. Given the two facts above, what is used to heat a building by a heating system?
Options are: A. engines; B. wind; C. insulation; D. photons; E. radiator; F. body heat; G. calcite; H. ice;
Answer:
E.