Evaluate each of the independent situations to determine the type of accounting change$($correction of$$ error, change in accounting$$ policy, or change in$$ estimate$)$ and the appropriate accounting treatment$($retrospective or$$ prospective$).$

d$.$A shipbuilder changes its revenue recognition policy from the point of receipt by the customer to when the ship leaves the factory shipyard. This change results from a change in shipping policy from F$.$O$.$B$.$ destination to F$.$O$.$B$.$ shipping point.$($Recall from introductory accounting that F$.$O$.$B$.$ means$$ "free on$$ board," and it refers to the point at which custody transfers from seller to$$ buyer.$)$

e$.$An electronics retailer has never accrued for warranties or product guarantees. A new consumer protection law comes into$$ effect, giving buyers of electronic products a guarantee against defects for $180$ days after purchase and the ability to return defective products to the retailer.

f$.$A clothing company that has been operating for $20$ years decides to obtain an external audit for the first time in order to meet the$$ bank's demands. The audit firm recommends that management report inventories at the lower of cost and net realizable$$ value, whereas the company has previously only tracked and reported inventory figures at cost$.$