Look at the diagram showing resistance and flow of electrons.

which labels best complete the diagram?
x: high resistance
y: low resistance

z: flow of electrons
x: low resistance
y: flow of electrons
z: high resistance
x: flow of electrons
y: high potential energy

z: low potential energy
x: low potential energy
y: high potential energy

z: flow of electrons

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