The cost that varies depending on the values of the decision variables is a: a. dual cost.
b. sunk cost.
c. relevant cost.
d. reduced cost.

The cost that varies depending on the values of the decision variables is a:

c. relevant cost.

Explanation:

The relevant cost affects a decision outcome.  It is not like the sunk cost, which is fixed in total, no matter the decision being made.  A relevant cost is also known as a differential or incremental cost, because it makes a different under some decision alternatives.  Relevant costs are important to consider whenever a business entity is making a buy or make decision.  Relevant costs have their unit costs fixed while the total costs vary according to the alternatives.

answer; experimentation;

answer; break-even analysis;