The text boxes below have been placed in a random order. Reorder the paragraphs.
A. But since ivory-yielding species are now endangered and protected by treaty, plastics are now almost exclusively used.
B. Piano keys are generally made of spruce or basswood.
C. Traditionally, the sharps (black keys) were made from ebony and the flats (white keys) were covered with strips of ivory.
D. Spruce is normally used in high-quality pianos.