How Is the Spectrum of a Bright-Line Emission Spectrum Changed

Multiple Choice

How is the spectrum of a bright-line emission spectrum changed from a cloud of interstellar gas that is moving away as opposed to a stationary one relative to us?

A) The bright lines will be shifted toward the blue part of the spectrum.
B) The emission spectrum would be turned into an absorption spectrum.
C) The bright lines will be shifted toward the red part of the spectrum.
D) Some bright lines would shift toward the red part of the spectrum and some would shift toward the blue part of the spectrum.