When we talk about evolution we come across the process of natural selection. Genetic variation is always required for the natural selection. A change or variation in the genes may help the individuals in a population to better adapt to the environment. Such changes may be brought by mutations or random mating in the population. Such variations help in the survival of the population by allowing them to adapt to changing environmental conditions.
Answer: water
Explanation: Water is everywhere and required to survive, so water would be the most abundant compound.
The machine found no kidney stones and the patient is healthy
