Calculate volume of the swim bladder as a percent of the total volume of the fish in order to reduce the average density of the fish from 1:067g=cm3 to 1:026g=cm3.

Answer(b) 60 miles per hour;

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

Ibelieve the answer is d. densityhope my answer has you : )