On August 31 of the current year, Harvey Co. decided to change from the FIFO periodic inventory system to the weighted- average periodic inventory system. Harvey uses U. S. GAP, is on a calendar year basis, and does not present comparative financial statements. The cumulative effect of the change is determined:
a. During the current year by a weighted average of the purchases.
b. During the eight months ending August 31, by a weighted average of the purchases.
c. As of August 31 of the current year.
d. As of January 1 of the current year.