Identify 3 specific situations in which machines make work easier

• Pushing a large & heavy refrigerator off a moving truck using a ramp.
• Harvesting various crops on a farm using a combine harvester.
• Gathering up large amounts of fish in a net & pulling the net in by using a pulley system.

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