What is the 'big bang' theory associated with?

The 'big bang' theory is primarily associated with the origin of the universe, as it proposes that the universe began from an extremely hot and dense state approximately 13.8 billion years ago and has been expanding ever since. This theory explains not only the formation of cosmic structures but also outlines how the universe evolved from its initial singularity into its current state. The evidence supporting this theory includes the cosmic microwave background radiation and the observed redshift of distant galaxies, which indicate that the universe is expanding.

The other choices relate to distinct scientific concepts. While the formation of stars is a subsequent process that occurred after the universe began to expand, it does not pertain to the inception of the universe itself. The evolution of species is a biological concept that explains the diversity of life on Earth, originating long after the universe had formed. Similarly, the development of Earth is a geological topic that focuses on the planet's history and does not encompass the broader cosmological events covered by the big bang theory. Hence, the correct association of the 'big bang' theory is indeed with the origin of the universe.