The electric field radiated at large distances in free space by a current-carrying small circular loop of radius a, placed on the xy plane at z 0, is given by cos (t r) for r » a , where eo is a constant, β○ wvaoeo, r is the radial dis- tance in spherical coordinates, and θ is the spherical angle measured from the z axis that is perpendicular to the plane of the loop. de termine the corresponding radiated magnetic field at large distances from the loop (r» a).

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