Final answer:
The reducing agent in a redox reaction loses electrons and also loses energy, which is the energy given to the molecule being reduced.
Step-by-step explanation:
The molecule that functions as the reducing agent (electron donor) in an oxidation-reduction (redox) reaction is the one that loses electrons. When a molecule loses electrons, it is being oxidized, and thus provides reducing power to the other molecule which is being reduced. According to the options provided, the correct choice would be that the reducing agent 'loses electrons and loses energy'.
Therefore, the correct option in the final answer is c. loses electrons and loses energy.