Passage Summary: We observe objects called quasars that are so far away their light takes 500 million years to reach us. For them to be visible, they have to be incredibly bright, but objects that bright burn out in only 100 million years.

Reasoning: Quasars are at least 500 million light years away, and to be visible from Earth, they must produce light equivalent to 90 billion suns; however, objects burning at that intensity cannot last longer than 100 million years.

Analysis: This is a classic 'Must be True' inference chain involving time and distance. Since the light we see today left the quasar at least 500 million years ago, and the quasar itself can only stay that bright for 100 million years, the object must have burned out long before its light reached our telescopes. You should look for an answer that concludes these quasars no longer exist in the state we are currently observing. The facts essentially force a conclusion about the current non-existence of the source.