Answer:
A valley fold is one where you fold the paper into itself. The paper should form a V when you unfold.
A mountain fold is where the paper is folded behind itself.
I think the answer is A, to serve in religious and political rituals.
Acoustic instruments.
Simple chord progressions such as C-F-G or Am-G.
Simple time signatures such as 3/4 or 4/4.
"Sharp" or natural keys such as C, D, E, G or A.
Simple scales such as pentatonic minor (blues), pentatonic major, major, melodic minor and mixolydian.
