Which of the following best defines the subdominant scale degree?

The subdominant scale degree is defined as the fourth degree of the scale, which is directly related to the tonic. In any diatonic scale, the tonic is the first scale degree, and counting up from the tonic, the fourth scale degree is referred to as the subdominant. This degree plays a crucial role in establishing harmonic progressions and adds tension that typically resolves back to the tonic.

For example, in the key of C major, the tonic is C, while the subdominant is F, the fourth note in the scale C-D-E-F. Understanding this relationship is essential for analyzing music theory and composition, as the subdominant often leads to the dominant scale degree (the fifth), creating movement within the music.