During a period of rising material costs, FIFO assigns the oldest and lower costs to cost of goods sold, while the newer and higher costs remain in ending inventory. This produces a lower cost of goods sold and therefore a higher gross profit and net income compared with average-cost methods. Specific identification depends on the actual units sold and does not necessarily produce the highest profit unless management selects lower-cost units. Weighted average smooths cost changes and usually produces profit between FIFO and newer-cost methods. Internal auditors should understand inventory valuation because it affects profitability, taxes, inventory carrying value, financial ratios, and management incentives. Since FIFO produces the highest profit in a rising-cost environment, Option C is correct.