What are the three different inventory cost flow assumptionscommonly used in com

What are the three different inventory cost flow assumptionscommonly used in commerce today and allowed by generally acceptedaccounting principles? How does a company determine what cost flowassumption they should use? How does first in first out cost flowassumption work? When it is most appropriate to use? How does lastin first out cost flow assumption work? When it is mostappropriate to use? How does an average cost flow assumption work?When it is most appropriate to use?