In 1953, S.L. Miller successfully simulated the conditions of...

In 1953, S.L. Miller conducted an experiment to test the biochemical origin of life (chemical evolution) proposed by Oparin and Haldane.

He created conditions similar to those of primitive Earth in a laboratory scale. He used a closed flask containing a mixture of simple gases: methane ($CH_4$), ammonia ($NH_3$), hydrogen ($H_2$), and water vapour at $800^{\circ}C$.

To simulate the lightning of the primitive Earth, which provided the energy for chemical reactions, he used electric discharge from electrodes in the flask.

This resulted in the formation of simple organic compounds like amino acids, supporting the theory of chemical evolution.

Answer: Electric discharge