Which one of the following statements about costs is correct?

The higher the total costs, the larger the net present value of a project.

Total costs will decrease as the variable cost per unit increases, all else held constant.

A decrease in total fixed costs will increase the net present value of a project, all else held constant.

An increase in the variable cost per unit will increase the contribution margin, all else held constant.

Total costs will be greater under the best-case scenario than under the base-case scenario.