A 3.0 kg block slides down a rough inclined plane of an angle 20 degree with the horizontal at a constant speed u=1.5 m/s. Calculate coeffecient of frictional force

The best description is: . nobody has any idea what q is.

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