The RNA world hypothesis states that the earlier life-forms had relied only on RNA (Ribonucleic Acid) for the purpose of catalyzing the chemical reactions, and storing the genetic information. This hypothesis was proposed by Leslie Orgel, Carl Woese, and Francis Crick.
This hypothesis states that long before the living forms evolved to use DNA as the genetic storage material, the RNA molecules served the purpose of both storing the genetic information and carrying out catalysis, but because of its instability, DNA evolved.
Hence, the answer is RNA world hypothesis.
It does in fact that's really what natural selection is all about it uses the characteristics that would better help the organism survive therefore making the species thrive
1 - The most common emission and byproducts that are generated by burning coal are carbon dioxide, nitrogen oxides and dioxides and CCPs in genearl (coal combustion products).
2 - Mercury is a heavy liquid metal with some toxical properties. When ingested (most commonly trough water) can be fatal [for further info search Mercury Poisoning]. Something I should also point out is that most of the contaminated water sources are residual waters.
Hope it helped,
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