Which of the following cost types would be considered in calculating discounted cash flow?

Which of the following cost types would be considered in calculating discounted cash flow?
1. Capital or one off costs
2. Periodic maintenance costs
3. Regular operational costs
4. Opportunity costs

A.
1, 2, 3

B.
1, 2, 4

C.
1, 3, 4

D.
2,3, 4