State True or False Though sunk costs involve physical cash out-flows, they are irrelevant for decision making.

True.  Costs are relevant for decision making when these are 1) Future costs and 2) Differs between or among alternatives.  Since sunk costs are costs that were already been incurred in the past, they are already irrelevant for decision making.

True. Sunk costs are irrelevant costs and should not be included in decision making process.