The 2003 Observation of a Very Distant Galaxy, the Light

Multiple Choice

The 2003 observation of a very distant galaxy, the light from which passed through a less distant galaxy cluster on its way to Earth, showed an overall blueshift. What is the significance?

A) The observation shows that the most distant galaxies have already started to fall back to the center of the universe (the Big Crunch) , and their light experiences a Doppler blueshift.
B) The mass density at Earth's location is larger than the mass density in the vicinity of the very distant galaxy, so light experiences a gravitational blueshift as it moves toward Earth.
C) The apparent blueshift is not unusual. Most distant galaxies look blue because of the predominance of blue stars in the early universe.
D) The gravitational blueshift experienced by the light approaching the cluster (at an earlier time) outweighed the gravitational redshift it experienced (at a later time) while moving away from the cluster. This suggests an outward cosmological acceleration.