• The genetic variation of natural populations is constantly changing from genetic drift, mutation, migration, and natural and sexual selection.
•  The Hardy-Weinberg principle gives scientists a mamatical baseline of a non-evolving population to which y can compare evolving populations.
• Hence, Hardy and Weinberg independently proposed Non-evolving population.
• So, correct answer is 'Non-evolving population'.

Chemotrophs are organisms that obtain energy by oxidation of electron donors. These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs). Evolutionary biologists posit that earliest organisms on Earth were chemoautotrophs like Archae bacteria that produced oxygen as a by-product and later evolved into both aerobic, animal-like organisms and photosyntic, plant-like organisms. Thus, option C is correct.
Therefore, correct answer is option C.