In the Laboratory,an Atom Emits a Spectral Line at a Wavelength

Multiple Choice

In the laboratory,an atom emits a spectral line at a wavelength of 400 nanometers.In the spectrum of a star,the same spectral line is found to have a wavelength of 410 nanometers.What can be said about the star?

A) It is hotter than the Sun
B) It is moving toward the Earth
C) It is moving away from the Earth
D) It contains elements that are not found on Earth