Which of the following best describes a subdominant function?

The subdominant function is primarily characterized by its tendency to lead to the dominant chord. This relationship is foundational in tonal harmony, where the subdominant—often represented by the IV chord in a major key—serves as a pivotal step toward the dominant (V chord). This movement creates a sense of tension and anticipation, which is resolved when the music progresses to the dominant. This progression from the subdominant to the dominant is a common pathway in Western music composition, reinforcing the tonal structure and hierarchy.

The other options address different harmonic functions or resolutions that do not accurately describe the role of the subdominant. For example, while the subdominant does interact with other chords, its primary function is not to resolve to the submediant or to move directly to the tonic without an intermediate step like the dominant. Establishing the tonic key refers more to the role of the tonic chord (I) itself rather than the subdominant function.