Which One of the Following Is an Ordinary Annuity, but Not

Which one of the following is an ordinary annuity, but not a perpetuity?

A) $75 paid at the beginning of each monthly period for 50 years
B) $15 paid at the end of each monthly period for an infinite period of time
C) $40 paid quarterly for 5 years, starting today
D) $50 paid every year for ten years, starting today
E) $25 paid weekly for 1 year, starting one week from today