In evaluating the gross profit method, a company could need to modify its gross profit percentage. Which of the following is not a modification reason:

Recognize known changes in the relationship between its gross profit and net sales.

Use of separate gross profit rate for each department or type of inventory that has a different markup percentage.

Company uses an average gross profit rate based on several past periods to smooth period-to-period fluctuations.

Changing cost estimated to current period to keep with market value.