Many candidates were distracted by D and there were quite a few comments from teachers suggesting that this should be accepted. But D is not true as in most cases the varying current will change the temperature of the wire causing a change in resistance. It is only true in the case that temperature is kept constant – and that is the correct statement of Ohm’s Law. C is an alternative statement of Ohm’s law, given that resistance is calculated from V/I in any particular situation.