Final answer:
The assertion is false; sunk costs are typically ignored in decision-making as they cannot be changed, but variable costs are relevant and should be considered.
Step-by-step explanation:
The statement that costs, revenues, and other factors may be relevant to a decision despite not varying among possible courses of action is false. When making a decision, it is typical to ignore sunk costs because they are fixed costs that the firm has already incurred and cannot recover regardless of future actions. Sunk costs are not relevant to the decision-making process. However, variable costs are subject to change and convey important information about the firm's current ability to cut costs and potential cost increases if production is ramped up. Therefore, these costs are relevant to decisions about future courses of action.