Why might a scientist use a magnet and small strainer when investigating the physical properties of a substance?

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

Ineed more information about  the question 

Iwould say the answer is b.  christians believed jesus was the messiah, or savior of man.  because most jews do not believe  in jesus