What is defined as pollution?

Pollution is specifically defined as the introduction of harmful substances or contaminants into the environment, which can adversely affect ecosystems, human health, and the overall balance of nature. This definition encompasses various forms of pollutants, including chemicals, waste, and noise, that disrupt the natural conditions of air, water, and soil.

The other options refer to processes that do not align with the definition of pollution. The removal of contaminants is a remediation process aimed at reducing pollution levels rather than being pollution itself. Natural decomposition of organic materials is an essential ecological process that contributes to nutrient recycling in ecosystems, and it does not introduce harmful substances. Lastly, an increase in biodiversity is generally a positive ecological outcome, signifying a healthy and balanced environment, rather than a pollution-related scenario.