Answer: a.FIFO inventory cost method
Explanation: The First-In-First-Out inventory costing method involves applying the price associated with the oldest inventory purchase to goods sold. When the FIFO inventory method is used, when the number of goods purchased for the oldest inventory is exhausted, the cost of goods sold is then associated with the next oldest inventory. With these cost inventory method, the ending inventory always moves closer to the current prices of goods since the older inventory cost is applied first.