The fact that quasars can be detected from distances where even the biggest and most luminous galaxies cannot be seen means that Select one: A. they must be in directions where intergalactic absorption by dark matter is minimum, allowing us to see them. B. they must be intrinsically far more luminous than the brightest galaxies. C. they have not been as redshifted by their motion as have galaxies, and hence they can still be seen. D. they must be in directions where gravitational focusing by the masses of nearer galaxies makes them visible from Earth.

Select light for the type of wave, adjust the wavelength so that the light is red, and increase the amplitude of the light to the max. then, select the start button at the source location to begin producing the waves. light is a form of electromagnetic wave, containing oscillating electric and magnetic fields. the wave amplitude detector mentioned above shows how the electric field oscillates in time at the location of the probe. the amplitude of the wave at the location of the probe is equal to the maximum electric field measured. how does the amplitude of the wave depend on the distance from the source?