N Pole to S Pole
13. Turn one of the bar magnets around so the magnets are N pole to S pole with an inch between.
14. Sprinkle the iron filings over the glass or plastic.
15. On a separate paper sketch the magnets. Show the lines made by the iron filings.

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