The negative effect humans have on the stability of the environment is mostly directly linked to an increase in

Explanation:

Machinery as an energy unit for agricultural work produces a negative impact on the environment on soils, waters and the atmosphere. ... In the exploitation process it exerts impacts such as: soil degradation, water pollution and pollution of the atmosphere.

true, i don't really know what you're asking but from the info you provided im guessing the answer is true.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).