If You Want to Check on What Conditions Were Like

Multiple Choice

If you want to check on what conditions were like in the universe a few hundred thousand years after the Big Bang, what sort of instrument would it be best to use:

A) a gamma-ray or high-energy x-ray telescope in orbit
B) a tank of chlorine deep inside the Earth
C) a small refractor (which gathers visible light) on a college campus, but pointed in just the right direction
D) an ultra-violet telescope in orbit around Jupiter
E) a satellite with infrared and microwave telescopes on board