I Am Measuring the Spectrum of the Stars in a Spectroscopic

Multiple Choice

I am measuring the spectrum of the stars in a spectroscopic binary system. When one of the stars is moving toward the Earth in its orbit, we observe

A) that the lines in its spectrum get brighter
B) that the lines in its spectrum merge with the lines of the other star
C) that it is no longer possible to learn what elements are in the star
D) that the lines in its spectrum show a blue-shift
E) none of the above