The correct answer is: B. Not relevant for decision making
Sunk costs are costs that have already been incurred and cannot be recovered. They are not relevant for decision making because they cannot be changed by any decision that is made. For example, if a company has already spent \$1 million on developing a new product, that \$1 million is a sunk cost and should not be considered when deciding whether or not to launch the product.
Option A is incorrect because sunk costs are not relevant for decision making. Option C is incorrect because sunk costs are not costs to be incurred in the future. Option D is incorrect because sunk costs are not future costs.
Sunk costs can be a difficult concept to understand, but they are important to understand when making decisions. When making a decision, it is important to focus on the costs and benefits that will be incurred in the future, and to ignore sunk costs.