After every three projects or so
1) plagal
2) this can be debated everywhere because it depends on what "makes sense" I think it is a phrase but it could just as easily be a measure. a period would be too long and a cadence, while making sense, is a cadence, it ends a phrase. The answer the answer key is looking for will probs be a phrase.
3) phrases, period (answer D)
4) A: Authentic
hope his helps! good luck with the rest of Music Theory!
