Which of the following statements is false?

1. When calculating a project's free cash flows, we generally include financing costs such as interest expenses
2. When calculating a project's cost of capital, we generally include financing costs such as interest expenses
3. Because the opportunity cost of using a resource for a project is the value the resource could have provided in its best alternative use, we should include the opportunity cost as an incremental cost of the project
4. Because sunk cost have been or will be paid regardless of the decision whether or not to proceed with a project, they should be excluded from incremental earnings of the project