Under what circumstances do generally accepted accounting principle permit the use of an inventory cost flow assumption? Must a cost flow assumption closely parallel the physical movement of the company's merchandise?

Please see the attached file.

1 Specific identification and Cost Flow Assumptions: concepts fully explained with example in a table form.
2 Cost flow Assumptions and actual flow of merchandise: FIFO, Average price and LIFO assumptions explained with numerical examples in separate tables to shoe ending inventory valuation and cost of goods sold under each assumption.
3 Cost flow assumption and Generally accepted accounting principles (GAAP) : Requirements of GAAP and impact of different cost flow assumptions fully explained with specific reference to Canadian income tax law requirement and international perspective.