The FIFO method of inventory accounting assigns the cost of the earliest units acquired to goods transferred out and the cost of most recent acquisitions to ending inventory. When prices are rising, the cheaper goods in beginning inventory reflecting earlier purchases are assigned to COGS (hence, higher income and higher shareholder's equity through retained earnings.)
Explanations for other choices:
In periods of rising prices and inventory levels (all else constant):
- FIFO firms have lower debt to equity ratios than LIFO firms do because stockholder's equity is higher and debt is constant.
- LIFO firms have lower gross profit margins ((Sales-COGS)/Sales) because the more expensive last purchases are assigned to COGS, lowering the numerator.