The correct answer is: They showed how organic molecules could be made from Earth’s early atmosphere.

The Miller-Urey experiments, conducted in the 1950s, simulated early Earth conditions and demonstrated that simple organic molecules, such as amino acids, could be synthesized from inorganic compounds using electrical sparks. This provided insight into how life’s building blocks could form spontaneously in the conditions present on early Earth, supporting the idea of abiogenesis as a potential origin for life, which is relevant to the broader theory of evolution.