Powell Company Had the Following Errors Over the Last Two

Powell Company had the following errors over the last two years: 2007: Ending inventory was overstated by $30,000 while depreciation expense was overstated by $24,000.
2008: Ending inventory was understated by $5,000 while depreciation expense was understated by $4,000.
By how much should retained earnings be adjusted on January 1, 2009? (Ignore taxes)

A) Increase by $15,000.
B) Decrease by $25,000.
C) Decrease by $6,000.
D) Increase by $25,000.