Bob is pushing a lawn mower up a hill with the mower tilting slightly to the right. suppose that we wish to use vectors to determine the total force acting on the mower. what forces should be considered?

Bob is pushing a lawn mower up a hill with the mower tilting slightly to the right. If we wish to use vectors to determine the total force acting on the mower. These are the forces that should be considered:

Force pushing the lawnmower 
Gravitational force 
Weight of the lawnmower pushing against the slope 
Counter force of the slope against the lawnmower

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