Acoustic instruments, Electrical instruments, Living beings like animals and birds using their vocal cords, Man-made sources like machines, any vibration caused by wind are five sources of sound
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The three most geometric shapes in paint are cirlcles, triangles, and squares.
Answer:
B
Explanation:
A commercial source might have a reason to lie, or bend the truth, for financial gain. With an anonymous author, you can't identify them, so you don't know if they would tell the truth or be right or not. An established record of research proves that the author knows how to find and state facts, and cares that their writings are accurate.
