In today's world, a very small portion of extinction is still caused by
natural events like volcanoes and earthquakes. In truth, humans are
contributing significantly to another widespread extinction event. Some say
that the extinction taking place today is occurring at a rate more than 100
times faster than it has in the past. In recent history, more than 800 species
have left the Earth forever. Thousands of creatures are still at great risk of
becoming extinct in our lifetimes.
-Excerpted from "A World at Risk" by Leonardo Eco
Which information is explicit in the text?
1.Before humans, a large portion of extinction was caused by
natural events.
2.Human beings are significant contributors to extinction.
3.In recent history, millions of species have left the Earth forever.
4.There are thousands of creatures not at risk of extinction.