In a design of a passenger bus it is proposed to derive the motive power from the energy stored in fly wheel. the fly wheel has a moment of inertia of 400kgm2 is accelerated to its maximum rate of rotation 3000 revolutions per minute by electric motors. calculate the maximum kinetic energy which can be stored in the fly wheel

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