Solution

The accelerated rates of species extinction are largely due to human activities. The major causes of biodiversity loss are termed as "Evil quartet".
1. Over-exploitation: Humans depend on nature for food and shelter but when the need turns into greed, it leads to over-exploitation of natural resources. For example, Steller's sea cow which became extinct due to overexploitation by humans.
2. Alien species invasion: When alien species are introduced for a specific purpose, some of them turn invasive and cause extinction or decline of indigenous species. For example, the Nile perch introduced into Lake Victoria in East Africa led to the extinction of more than 200 species of cichlid fish in the lake.
3. Habitat loss and fragmentation: This is the most common cause of the extinction of animals and plants. The most dramatic example of habitat loss is the tropical rainforests. Once covering more than 14% of earth's land surface, these rainforests now don't cover even 6% of the land surface.
4. Co-extinction: When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct and this is known as co-extinction. For example, in plant-pollinator mutualism, extinction of one leads to the extinction of other.
So, the correct answer is 'Habitat loss and fragmentation'.