You are currently operating at a volume of 2,000 units with fixed costs of $200,000 and variable costs of $20,000. You have asked your analyst, Jeff, to estimate costs at a volume of 5,000 units. He estimates that at that volume, fixed costs would be $200,000 and variable costs would be $50,000. As you consider the possible accuracy of his fixed cost estimate, which one of the following concepts is most relevant?

a) Relevant range

b) Breakeven point

c) Contribution margin

d) Product margin