The correct answer is (d). Natural habitat destruction is the main reason for the decrease in biodiversity.
Habitat destruction is the permanent removal of an organism’s natural habitat. This can be caused by human activities such as deforestation, mining, and urban development. Habitat destruction can lead to the extinction of species, as well as the decline of populations of many other species.
Habitat pollution is the contamination of an organism’s natural habitat with harmful substances. This can be caused by human activities such as industrial pollution, agricultural runoff, and oil spills. Habitat pollution can lead to the death of organisms, as well as the decline of populations of many other species.
Introduction of exotic species is the introduction of a species to an area where it does not naturally occur. This can be done intentionally, such as when a species is introduced to control pests, or unintentionally, such as when a species is transported on a ship or airplane. Introduction of exotic species can lead to the decline of native species, as the exotic species may compete with them for food and resources, or prey on them.
Overexploitation is the use of a resource at a rate that is greater than the rate at which it can be replenished. This can be caused by human activities such as hunting, fishing, and logging. Overexploitation can lead to the extinction of species, as well as the decline of populations of many other species.
In conclusion, the main reason for the decrease in biodiversity is natural habitat destruction.