Carter, Inc. can make 100 units of a necessary component part with the following cost. If Carter can purchase the component externally for $220,000 and only $10,000 of the fixed costs can be avoided, what is the correct decision? A) Buy because operating profit will be $30,000 higher. B) Buy because operating profit will be $10,000 higher. C) Make because operating profit will be $10,000 higher. D) Make because operating profit will be $30,000 higher. A cost that cannot be changed by any present or future decision is a(n) A) variable cost. B) irrelevant cost. C) opportunity cost. D) incremental cost