Castle Incorporated has the following information about three costs, A, B, and C:

	Month	Amount	Units
Cost A	January	$ 68,000	136,000
February	$ 136,000	272,000

	Month	Amount	Units
Cost B	January	$ 37,000	40,000
February	$ 37,000	80,000

	Month	Amount	Units
Cost C	January	$ 74,000	59,200
February	$ 103,600	118,400

Required:

Indicate whether these costs are variable, fixed, or mixed.