please show work. i will upvote.

13. Suppose that there is a zero-coupon bond that will pay $1,000 sometime in the future. If this bond is trading at $800 and the yield-to-maturity on this bond is 5%, what is the maturity of this bond? Assume annual compounding. a) 2.48 years b) 4.57 years c) 6.21 years d) 8.78 years e) Not enough information