Mitigation is defined as actions taken to prevent or reduce the occurrence of natural disasters and damage to an environment. Restoration is the renewal of an environment or ecosystem after it has been almost or completely destroyed. Preservation is a collection of efforts aimed at sustaining a vulnerable or unstable ecosystem. Remediation is often the clean up or removal of contaminants from an environment. 

The correct response is biodiversity conservation. Pollution alters ecological communities by adding harmful chemicals, substances, and abiotic factors into the environment. This has a negative effect on biodiversity - not a positive effect. Thus, we would not except for species to be conserved in a region with pollution. We know that pollution can lead to acid rain, contaminated water, and ozone depletion so those answer choices are incorrect.

Rachel Carson's Silent Spring focused primarily on the widespread application of pesticides, the lack of government regulation of said pesticides (especially DDT), and their negative impacts on bird populations (i.e. songbirds that were at risk and would result in a spring lacking their songs). The book challenged industry claims that downplayed toxicity of their products and triggered a grassroots environmental movement that helped create the U.S. Environmental Protection Agency. 

Fertilizer runoff can cause eutrophication, where nutrient-enriched freshwater mixes with saltwater and causes huge algal bloom, such as red tide. These can be toxic to both ocean organisms and to humans. 

Tuberculosis has an airborne mechanism of transmission. Cholera, typhoid, polio, and meningitis are all diseases capable of waterborne transmission.

Bioaccumulation is the process of a toxin entering an organism at a rate faster than it is evacuated. Toxins from food poisoning are expelled by the body's response to evacuate the substance, while mercury in seafood or lead in waterfowl populations tend to accumulate over time.

A primary pollutant comes from a direct source, while a secondary pollutant is formed by chemical reactions from primary pollutants in the environment.  (sulfuric acid) is a product of chemical reactions in the environment, producing acid rain.

A teratogen is most likely to cause a birth defect. Exposure to a teratogen specifically causes deformities in an embryo.

Ozone is created when sunlight reacts with nitrous oxides and other pollutants, many of which originate from gasoline vapors, combustion products, etc. It is harmful when breathed. On hot days, some metropolitan areas issue smog warnings.

Lead, a heavy metal, accumulates in the body. Children are especially susceptible to airborne lead. Iron, also a metal, can be problematic in large quantities, but is also necessary in extremely small amounts for proper function.