The core idea
Existing fixed-rate bonds generally gain value when comparable market rates fall because their contractual cash flows become more attractive. Long-duration bonds tend to respond more strongly.
What is happening underneath
Callable bonds can behave differently because falling rates increase the chance that the issuer refinances and redeems the bond early.
How investors should read it
Lower rates can therefore create price gains while simultaneously increasing reinvestment and call risk.
The same market move can carry different information depending on which maturity, issuer and risk premium is changing. Read the question together with the underlying concepts rather than treating one price move as a universal signal.