Which of the following statements is true about cosmic microwave background radiation?

The statement that cosmic microwave background radiation is the same temperature everywhere is correct because this radiation is a relic from the early universe, specifically from the time shortly after the Big Bang. The cosmic microwave background (CMB) is a uniform field of radiation that fills the universe and has a remarkably consistent temperature of about 2.7 Kelvin. This uniformity is a key piece of evidence supporting the Big Bang theory, as it indicates that the early universe was hot, dense, and in thermal equilibrium.

While there are minor fluctuations in the temperature of the CMB—often referred to as anisotropies—these variations are extremely small compared to the overall uniform temperature across the cosmos. The CMB is not produced by solar flares or nuclear reactions in stars; instead, it is left over from the time when the universe became transparent to radiation, allowing photons to travel freely. These characteristics highlight the significance of the CMB as a fundamental component in understanding the evolution of the universe.