At a production volume of 10,000 units, Grist Company incurs a total cost of $30,000 ($10,000 in fixed cost, and $20,000 in variable cost). If the production volume is 12,000 units, the total cost will be:

	A.	$34,000
	B.	$30,000
	C.	$36,000
	D.	$24,000

Carla Company incurred four costs. For each of them, the costs in total at different production levels are shown below.

	Production level
	100 units	200 units	300 units
Cost A	$20,000	$40,000	$60,000
Cost B	$30,000	$40,000	$50,000
Cost C	$30,000	$30,000	$30,000
Cost D	$30,000	$30,000	$50,000

Most likely, which of the above costs is a mixed cost?

	A.	Cost A
	B.	Cost B
	C.	Cost C
	D.	Cost D