When the signal s(t) is defined for all values of time within a specified interval, what type of signal is it?

When the signal s(t) is defined for all values of time within a specified interval, it indicates that the signal can take on any value at every instant of time, therefore classifying it as a continuous time signal. Continuous time signals are characterized by their ability to be defined at every point in time, meaning they don't have gaps or discrete intervals. This is in contrast to discrete signals, which are only defined at specific time instances.

The other options do not fit the description as directly as continuous time signals do. A bandpass signal is a specific type of signal that is confined to a particular frequency range, while an information signal generally refers to any signal that conveys information, which could be either continuous or discrete. A continuous frequency signal refers to the frequency domain representation and does not describe the time-domain characteristics of the signal itself. Thus, the provided answer aligns with the fundamental definition of continuous time signals.