What is a serious problem of Lake Baikal in Russia

Câu hỏi:

What is a serious problem of Lake Baikal in Russia?

A.
The government did not have the power to enforce laws and regulations.

B.
It has 1,300 rare species that do not exist anywhere else in the world.

C.
It contains a rich variety of animals and plants.

D.
It is polluted by massive volumes of industrial wastes discharged into it.

Đáp án đúng: D