Which of the following describes the difference between continuous and discrete signals?

The correct choice articulates that continuous signals can take on any value within a given range, making them smooth and flowing, like waveform representations of sound or light intensity. This characteristic allows for an infinite number of points along the time axis, enabling a very accurate representation of real-world phenomena. On the other hand, discrete signals are defined at specific intervals or points in time, meaning they can only take on certain predetermined values. This distinction is pivotal in fields such as digital communications and signal processing, where understanding the nature of the signals being dealt with directly impacts the methods of analysis and processing that can be applied.

In contrast, the other options do not accurately reflect the technical definitions or implications surrounding continuous and discrete signals. For instance, continuous signals are not inherently digital; rather, they are often analog. The notion that continuous signals can be easily modified while discrete signals cannot also lacks a clear relationship to the definitions of the signals themselves, as both types can be manipulated in various ways depending on the context and application. Finally, stating that there is no difference between the two signals is fundamentally incorrect, as the very definitions of continuous and discrete highlight their distinct characteristics.