Hulk Company reports the following

                                      2008           2009
Sales                             $300,000    $360,000
Cost of goods sold             $75,000      $90,000

Based upon this information which of the following is most correct:

A) Cost of goods sold is a permanent cost

B) Cost of goods sold is a economic cost

C) Cost of goods sold is a totally variable cost

D) Cost of goods sold is a period expense