C is corrent. The requirement is to identify the types of bonds that are most likely to maintain a constant market value. A bond with a floating rate will generally hold a steady market value because its value will not change due to changes in prevailing interest rates.
A is incorrect because a callable bond has a fixed interest rate and its market value fluctuates with changes in prevailing interest rates.
B is incorrect because a zero-coupon rate bond increases in value as it approaches its maturity.
D is incorrect because a convertible bond has a fixed interest rate and is convertible into stock. Therefore its market value fluctuates with both changes in prevailing interest rates and changes in the value of the stock.
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