What is an imperfect authentic cadence?

• A. V to I where the I is in root position.
• B. V to I with both chords in root position.
• C. V to I where the I is in a non-root position or tonic in the upper voice; not both chords in root position.
• D. I to V.

Answer: (C)

An imperfect authentic cadence is a dominant-to-tonic resolution that isn’t as decisive as a perfect one. In a perfect authentic cadence, both chords sit in root position and the final tonic is clearly voiced, typically with the soprano ending on scale degree 1. When that strong voicing isn’t achieved, the cadence still feels like a resolution to I, but with less finality.

The described situation fits this idea: you have a V moving to I, but the I chord isn’t in root position, or the tonic is placed in the upper voice (the soprano) in a way that doesn’t align with the strongest, most conclusive ending. Because one of the strongest criteria for a perfect authentic cadence isn’t met, this is categorized as imperfect. The emphasis is on the resolution happening, but not with the full, final weight of a perfect authentic cadence.