What characterizes an analog signal?

An analog signal is characterized by its ability to vary continuously over a range of values. This continuous nature allows it to represent changes in physical phenomena, such as sound, light, or temperature, seamlessly. Unlike digital signals, which operate using discrete values and represent information in binary form (0s and 1s), an analog signal can take on any value within a given range, providing a more fluid representation of information. This is particularly evident in applications such as audio transmission, where sound waves can be represented as varying voltage levels without abrupt changes, enabling a natural and smooth transition of sound.

The other options do not align with the characteristics of an analog signal: the notion of staying constant does not apply since analog signals are defined by their variability, using discrete values pertains to digital signals, and the concept of being always digital contradicts the fundamental definition of an analog signal.