A bus is designed to draw its power from a rotating flywheel that is brought up to its maximum rate of rotation (3060 rev/min) by an electric motor. The flywheel is a solid cylinder with a mass of 1060 kg and diameter 0.96 m. If the bus requires an average power of 9.4 kW, how long does the flywheel rotate

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