When interest rates fall, an investor who owns a callable bond faces the risk that the bond will be called and the proceeds must be reinvested at lower rates. This combined concern is BEST described as:

Giải thích

When rates fall, issuers often call bonds to refinance cheaper, forcing the investor to reinvest the returned principal at the now-lower market rates, so call risk gives rise to reinvestment risk. This is unrelated to inflation, default, or exchange rates.