Which of the following pieces of evidence best supports the Big Bang Theory?

• A. The observation of cosmic microwave background radiation
• B. The presence of oxygen in Earth's atmosphere
• C. The regular phases of the Moon
• D. The constant temperature of Earth's core

Answer: (A)

Verified step by step guidance

1. Understand that the Big Bang Theory is a cosmological model explaining the origin of the universe from a hot, dense initial state.
2. Identify that evidence supporting the Big Bang Theory must relate to large-scale features of the universe, such as its origin, expansion, or early conditions.
3. Evaluate each option: the presence of oxygen in Earth's atmosphere, the regular phases of the Moon, and the constant temperature of Earth's core are all phenomena related to Earth and do not provide evidence about the universe's origin.
4. Recognize that the observation of cosmic microwave background radiation is a remnant heat signature from the early universe, providing strong evidence for the Big Bang Theory.
5. Conclude that the cosmic microwave background radiation best supports the Big Bang Theory because it matches predictions about the universe's early state and subsequent cooling.