请根据下面短文回答第下列各题： Temperatures(温度)around the world are going up year after year. A report shows that the ten wan nest years since 1860 all happened after 1987. Of those ten, nine happened after 1990. There port also says the increase(上升) in temperature over the past 25 years is greater than that over the past 1,000 years. Ken Davidson, a world-famous scientist, agrees with the scientific findings that global (全球的) warming is happening just because of what people do on the earth. He says one of the most important reasons for the higher temperatures is the fact that cities are getting bigger and bigger. Studies show that cities are hotter than other places. Reports Show that many places around the world have had unusual weather in the past few years because of global warming. Most of Asia, for example, is warmer than before, and in India hundreds of people have even died from the hot and dry weather each year. Parts of Africa have of-ten had unusually heavy rains while other parts of Africa have had unusually dry weather. In parts of Europe, more than 100 people died from heavy rainfall in September 2002. Yet large parts of North and South America had very dry weather in the same year. What is the text about?
A.Big cities.
B.Global warming.
C.A famous scientist.

A.Big
B.
B.Global
C.
C.A
D.