Which progression represents an authentic cadence in traditional tonal harmony?

• A. I-V or i-V
• B. V-I or v-i
• C. IV-I or II-V
• D. ii-V

Answer: (B)

An authentic cadence centers on a strong resolution to the tonic, created by moving from the dominant to the tonic. In traditional tonal harmony, the dominant chord (built on the fifth scale degree) contains a leading-tone that wants to resolve upward to the tonic, giving a convincing sense of closure. In major keys this is typically a V moving to I, and in minor keys the dominant is usually made major (V) to provide that leading-tone resolution to i. This V–I (or v–i with the appropriate harmonic minor context) is what gives the cadence its definitive, conclusive feel.

Other progressions don’t deliver that same sense of finality. Moving from tonic to dominant starts the phrase away from rest, rather than ending it; a progression like IV–I is a plagal cadence with a softer sense of closure; and II–V leads toward the dominant but ends on V, not the tonic, so it doesn’t itself function as the closing cadence.