Many new headphones on the market are called "noise reducing" because they take sound waves that come in from the outside and add a sound wave to it that is exactly opposite (out of phase) to it, these add together to make no noise. this is a good example of sound wave. a) absorption. eliminate b) diffraction. c) destructive interference d) constructive interference

whichever one it is, it's definitely not one that you included on the list you provided.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.