Water, initially saturated vapor at 4 bar, fills a closed, rigid container. the water is heated until its temperature is 4008c. for the water, determine the heat transfer, in kj per kg of water

 Determine the initial temperature (T1) of the 10 kg of saturated vapor. Then the energy transfer is just the increase in energy = (mCp(T2-T1))

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current