A "fallen angel" is a bond that has moved from?
a) being publicly traded to being privately traded.
b) being a long-term obligation to being a short-term obligation.
c) having a yield-to-maturity in excess of the coupon rate to having a yield-to- maturity that is less than the coupon rate.
d) senior status to junior status for liquidation purposes.
e) investment grade to speculative grade.