What is the main idea of the news item？A．The pollution across the world is more and more s

What is the main idea of the news item？

A．The pollution across the world is more and more serious.

B．Natural disasters in some countries are more frequent.

C．Global warming will cause serious problems on the earth.

D．Countries along the sea coast are stricken by heavy rain.

请帮忙给出正确答案和分析，谢谢！