Castle Inc. has the following information: Month Amount Units Cost A January $45,000 40,000 February $ 45,000 80,000 Month Amount Units Cost B January February $ 90,000 $126,000 72,000 144,000 Month Amount Units Cost C January $100,000 200,000 February $200,000 400,000 Indicate whether these costs are variable, fixed, or mixed. Cost A Cost B Cost C