Which One of the Following Best Describes the Concept of Erosion

Which one of the following best describes the concept of erosion?

A) expenses that have already been incurred and cannot be recovered
B) change in net working capital related to implementing a new project
C) the cash flows of a new project that come at the expense of a firm's existing cash flows
D) the alternative that is forfeited when a fixed asset is utilized by a project
E) the differences in a firm's cash flows with and without a particular project