Answer: Man's direct activities
Explanation:
Man activities are the major cause of mass extinction, especially activities such as bush burning and deforestation for agricultural activities that threatens the natural habitats of certain species. Even climate change is also subject to mans activities.
Recent research reports that about 26% of previously forested regions have been deforested for agricultural activities, the Californian and Australian wild fires are all human mediated activities that can result in mass extinction of spec.