Explain why sunk costs should not be included in a capital budgeting analysis but opportunity costs and

Question:

Explain why sunk costs should not be included in a analysis but opportunity costs and externalities should be included.

Capital Budgeting
Capital budgeting is a practice or method of analyzing investment decisions in capital expenditure, which is incurred at a point of time but benefits are yielded in future usually after one year or more, and incurred to obtain or improve the...