Which of the following statements is CORRECT? a. A time line is not meaningful unless all cash flows occur annually. b. Time lines are useful for visualizing complex problems prior to doing actual calculations. c. Time lines cannot be constructed in situations where some of the cash flows occur annually but others occur quarterly. d. Time lines cannot be constructed for annuities where the payments occur at the beginning of the periods. e. Some of the cash flows shown on a time line can be in the form of annuity payments, but none can be uneven amounts.