What is the significance of the cosmic microwave background

What is the significance of the cosmic microwave background radiation discovered by Penzias and Wilson in 1964?

a. It is the remnant of a burst of radiation released during the early history of the universe.

b. It was the first radio transmission believed to indicate the presence of extraterrestrial life in the universe.

c. It showed a connection between millisecond pulsars and X-ray bursters.

d. It indicated the difference between Type I and Type II Cepheid variable stars.

Solution

The cosmic microwave background radiation is the remnant of a burst of radiation released during the early history of the universe. The radiation is isotropic. So, it discards the other three options.