There is a 120 V circuit in a house that is a dedicated line for the dishwasher, meaning the dishwasher is the only resistor on that circuit line. If the dishwasher draws 18 A of electricity, what would the resistance of the dishwasher be? Round the answer to the nearest hundredth of an ohm. Ω

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