Question

Every year _______ species go extinct.
a.
3
b.
72
c.
1000
d.
20000

Answer 1

It is kind of hard to estimate because for that first of all the number of species present on earth should be known. 

If we estimate the species with the help of World Wide Fund for Nature, which is an organization which is working towards fighting with the problem of animals going extinct their estimate of species going extinct is around 200-100 000 so the answer to this question is option D which is 20,000

Answer 2

Some of the scientists believe that around 150-200 species are going extinct, let it be plants, animals, mammals etc.

And each year the percentage of species which go extinct is around 0.01% year which is at least 10,000 species go extinct every year. 

So the answer to this question is 20,000 which is closest to 10,000.