Can you help me on this please

Which property of fossils allow scientists to determine the relative rock ages..

Which of the following will cause an induced current in a coil of wire? the constant field of the earth passing through the coil a magnet resting near the coil a magnet being moved into or out of the coil a wire carrying a constant current near the coil

Which wave would cause destructive interference at every point of the wavelength and completely cancel out the wave?