How old is the universe estimated to be?

The universe is estimated to be approximately 13.7 billion years old based on various scientific methods of dating cosmic events and structures. One major piece of evidence comes from the observation of the cosmic microwave background radiation, which is the remnant heat from the Big Bang. This radiation provides a snapshot of the universe when it was just about 380,000 years old, allowing astronomers to extrapolate backward and determine an age for the universe.

Additionally, the measurement of the expansion rate of the universe, known as the Hubble constant, and the study of the oldest star clusters contribute to the age estimation. The oldest known star clusters, like globular clusters, reveal ages that also support the 13.7 billion-year figure. The other options provided do not align with the most current understanding of cosmic age, as they refer to either the age of the Earth or do not reflect the consensus of cosmological research.