How Are Investors in Zero-Coupon Bonds Compensated for Making Such

How are investors in zero-coupon bonds compensated for making such an investment?

A) Such bonds are purchased at their face value and sold at a premium at a later date.
B) The bond makes regular interest payments.
C) Such bonds are purchased at a discount to their face value.
D) The face value of these bonds is less than the value of the bond when the bond matures.
E) Bond prices always increase over time.