Which one of the following is an ordinary annuity ? 0 1) $50 paid weekly for 1 year, starting one week from today O 2) $40 paid quarterly for 5 years, starting today O 3) $25 paid every year for ten years, starting today 04) $75 paid at the beginning of each monthly period for 50 years 5) $15 paid at the end of each monthly period for an infinite period of time