Answer:
The principal types of such instruments, classified by the method of producing sound, are percussion, stringed, keyboard, wind, and electronic
Answer: d. (1) values; (2) depth
Those are scales. the highlighted notes (aka the guide tones) are notes in that specific chord that give a harmonic pull towards the next chord. generally they are the 3rd and 7th note (that’s what determines what type of chord it may be: major, minor, major-minor, or dominant). they are the most harmonically important notes in the chord since they determine the quality of the chord itself, so make sure they are in perfect tune.
I tried to make a visual explanation to this. Thanks to Musescore and Windows Paint, the result is highly appealing from a visual point of view.
