Answer:
A. considered irrelevant to the decision.
Step-by-step explanation:
The essence of decision making is to get best value considering the various elements of cost involved.
Cost that do not differ between alternatives are considered irrelevant to decision making as such cost (where necessary for project) will be incurred without a loss or gain in the amount spent. Opportunity cost refers to the cost of the alternative forgone but this question talks about cost that do not differ between alternatives hence option C is not right.
Cost are not only considered when they represent a material dollar amount rather they are considered on the basis of their importance to the project.
Therefore considering all the options, the right answer is A as Costs that do not differ between alternatives are considered irrelevant to the decision.