Answer:
The correct option is;
The star is moving toward Earth.
Step-by-step explanation:
The shifting of the wavelength of light wave toward the blue end of the electromagnetic spectrum is termed blue shift.
A blue-shift of an electromagnetic wave corresponds to the wavelength decrease of the wave, which is equivalent increase in energy, resulting in an increase in the observed frequency of the wave.
Astronomers make use of the shifting of the wavelength of a wave to understand the relative motion of galaxies.
The wavelength of an approaching electromagnetic ave shifts towards the blue end of the electromagnetic spectrum because the wavelength is shorter.
The opposite of phenomenon is red-shift.