A company’s gross profit as a percentage of sales increased from 28% in the year ended 31 December 2005 to 33%
in the year ended 31 December 2006.
Which one of the following could have caused the increase?
A   An increase in sales volume.
B   Understatement of closing inventory at 31 December 2005.
C   Overstatement of closing inventory at 31 December 2005.
D   Goods received in December 2005 and included in inventory at 31 December 2005 were not recorded in
      purchases until January 2006.

B