The correct option is D All of the above
Unlike in the past, when mass extinctions were caused by events like asteroid strikes, volcanic eruptions, etc., 99 percent of the currently threatened species are at risk due to human activities like hunting and overexploitation.
Deforestation refers to the indiscriminate cutting, clearing, and removal of rainforests or related ecosystems into less biodiverse ecosystems such as pasture, cropland, or plantations.
Toxic chemicals and heavy metals flow into the ocean when industrial, agricultural and human wastes run off or are deliberately discharged into rivers, which then empty into the sea. These pollutants can cause disease and genetic mutations. In many cases, animals near the top of the food chain are most affected because of biomagnification (Biomagnification refers to the increasing concentration of a substance, such as a toxic chemical, in the tissues of organisms at successively higher levels in a food chain.)