How does the concept of an octave relate to musical scales?

The concept of an octave is fundamental to musical scales as it establishes a framework for their construction. An octave is a specific interval between one musical pitch and another that is either double or half its frequency. This relationship is crucial because it forms the basis for how scales are structured.

In most Western music, scales are built using a series of pitches that repeat at intervals of octaves. For example, the C major scale consists of the notes C, D, E, F, G, A, B, and then C again at a higher pitch. The repeating nature of the octave allows musicians to create multiple octaves of the same scale, maintaining the same intervals between notes at different pitch levels.

Additionally, the octave helps in categorizing notes within broader structures like diatonic and chromatic scales, providing a system for how notes relate to each other across the musical spectrum. This foundational aspect makes option C the correct choice, as it highlights how the concept of an octave is integral to the construction and comprehension of musical scales.