Consider a complete circuit made of an (ideal) battery and a resistor. Which one of the following statements about the work that the battery does is true?
A. The work done is equal to the thermal energy dissipated by the resistor.
B. The work done is equal to the work needed to move a single charge from one side of the battery to the other.
C. The work done is equal to the emf of the battery.
D. No work is done by the battery.
E. The work done is equal to the product of the current flowing through the circuit and the resistor.