1. The right answer is bioremediation
Bioremediation is a technique of increasing biodegradation or biotransformation by inoculating specific microorganisms (bioaugmentation) or by stimulating the activity of native microbial populations by biostimulation, nutrient supply and environmental conditions ( oxidation-reduction potential, humidity).
2. The right answer is a.the competition for resources increased in the ecosystem.
In the field of biology, the competitive relationship is the rivalry between living species for access to the limited resources of the environment. It is part of biotic factors and therefore of relationships between living beings. It can be interspecific (between members of different species) as it can be intraspecific (between members of the same species).