In 1953, stanley miller

In 1953, scientist Stanley Miller performed an experiment that may explain what occurred on primitive Earth billions of years ago. He sent an electrical charge through a flask of a chemical solution of methane, ammonia, hydrogen and water. This created organic compounds including amino acids.

Making amino acids is tricky, even in the laboratory. We know amino acids exist in some kinds of meteorites and interplanetary dust particles. When they rain down on a planet's surface, they import the possible building blocks of life, not necessarily life itself. Scientists think that along the way, there must have been a crucial step that turned atoms into organisms, but they still don't know what it is.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

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