A harmonic oscillator will have a maximum response when an outside force pushes it at the same frequency at the natural frequency of the oscillator A student drives his old car along a road in which contraction lines are etched in the concrete every 47 meters. The driven finds that his car shakes violently when he drives at 28 m/s. Based on this information, what is the natural frequency of the car's vibrations

Wind or electric energy force force of friction

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