A water holding tank measures 95 m long, 40 m wide, and 12 m deep. Traces of mercury
have been found in the tank, with a concentration of 60 mg/L.
What is the total mass of mercury in the
tank?
Answer in units of kg

Your answer is 1.5 hope i  

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

Answertechnician (a) is correct;