Which of the following securities is most susceptible to interest rate risk?
A. straight preferred stock
B. convertible preferred stock
C. convertible debentures
D. common stock
EXPLANATION: bonds and preferred stock are subject to interest rate risk--rates up, market price down. They pay a fixed rate of return, so whenever interest rates on new fixed income securities go up, the market values of existing fixed income securities drop. Every single time. Common stock doesn't pay a fixed rate of return, so interest rates are not as relevant to its market price. The market price for common stock is based on expectation of future profits, with bits of news driving those expectations up and down every day.
All righty then. Using these fundamental concepts, we can eliminate common stock, and then, since common stock drives the value of convertible preferred and convertible bonds, we can eliminate those two choices, too. We're left with straight preferred stock, which pays a fixed rate of return, period.