Which type of signal is characterized by varying continuously?

The characterization of a signal that varies continuously corresponds to an analog signal. Analog signals represent information in a continuous form, meaning that their values can take on any number within a given range. This allows for a smooth and gradual change, which is essential for representing phenomena like sound, light, and temperature accurately.

In contrast, digital signals are discrete and can only take on specific values, typically represented as binary code (0s and 1s), making them suitable for computer and digital communication applications. Pulsed signals consist of distinct pulses or bursts, rather than a continuous waveform. Static signals, on the other hand, do not change over time, indicating that they remain constant.

Thus, the defining feature of an analog signal as one that varies continuously makes it the correct answer to this question.