Which Statement Is Most Accurate Regarding a Constant Current Stimulator

Which statement is most accurate regarding a constant current stimulator?

A) There is no such device as a constant current stimulator.
B) Constant current stimulators produce harmful levels of current when the resistance of the electrode has decreased.
C) The voltage increases to maintain the same level of current when the resistance increases.
D) Constant current stimulators produce current that does not vary, regardless of resistance.