What is the significance of einstein's famous equation e = mc2?

a) energy is not related to mass.
b) mass can be destroyed.
c) energy can be destroyed.
d) mass and energy can convert to one another.

D) mass and energy can be converted to each other.

Also note that the conversion factor is C^2

where:  E = m c^2 

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