IELTS Reading: Lựa chọn đúng sai, chủ đề "Extinction"

Read the following passage about the extinction of species.

There are a variety of factors that can contribute directly or indirectly to the extinction of a species. Extinction may come suddenly when an otherwise healthy species is wiped out completely, such as when toxic pollution renders its entire habitat unlivable, or it may occur gradually over thousands or millions of years, such as when a species gradually loses out in competition for food to better adapted competitors. Extinction may occur a long time after the events that set it in motion, a phenomenon known as extinction debt.

Currently, environmental groups and some governments are concerned with the extinction of species caused by humanity, and they try to prevent further extinctions through a variety of conservation programmes. Humans can cause extinction of a species through over-harvesting, pollution, habitat destruction, introduction of invasive species (such as new predators and food competitors), and over-hunting.

Are the following statements true, false, or not given?

1. In most cases of extinction, the species slowly dies out over a period of many years.
2. 'Extinction debt' refers to cases of species dying out long after the initial event that triggered the extinction took place.
3. Human activity is the principal cause of the extinction of species.