In paragraph 2, the word "it” refers to ____.

A. A fifth of all the birds in the world live in the rainforest.

B. 20% of all the animals in the world live in the rainforest.

C. Nearly two million species of insects are found in the Amazon rainforest.

D. Nearly half of the world's species of plants grow there.

A. chamber

B. flat

C. area

D. studio

A. human-related effects

B. some species

C. low birthrates

D. natural obstacles

A. reduced considerably

B. put a tick

C. examined carefully

D. motivated to develop

A. remove their wax coating

B. kill off bacteria

C. maintain their color

D. crack their skin

A. small flakes

B. fine powder

C. dried soup

D. recognizable pieces