A car travels 20 km South, then turns and travels 30 km East? What is the total displacement?

Explanation:36.05 km

Given

First car travels South

then turns and travels east

Suppose south as negative y axis and east as positive x axis

So,

Displacement is the shortest between initial and final point

Dispalcement

Displacement

Displacement

Magnitude

Magnitude

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