The correct answer is Option #4: Average Cost would be most
suitable inventory methods in a gas station.
This is because its not feasible to apply specific
identification method because one can not determine that gas filled
to a customer is filled from the gas received on some specific
date.
FIFO and LIFO are not applicable because of the same reason.
Gas/Fuel when received is stored in a common tank and its not
possible to say that when gas is sold to customer, it is sold from
earlier purchases or from latest purchases.