Which of the following is not an observed characteristic of the cosmic microwave background?

A) It contains prominent spectral lines of hydrogen, the primary chemical ingredient of the universe.
B) It has a perfect thermal radiation spectrum.
C) Its temperature is a little less than 3 Kelvin (3 degrees above absolute zero).
D) Its temperature is the same everywhere, except for small variations at the level of 1 part in 100,000.


A

Physics & Space Science

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