Which of the Following Observations Is True

Which of the following observations is true?

A) Sunk costs are irrelevant for any future action.
B) Sunk costs should not be ignored when making decisions.
C) Sunk costs should be included when weighing the marginal costs of production against the marginal benefits received.
D) Sunk costs can be recovered using corrective measures.
E) Sunk costs are the same as social marginal costs.