
Passage: Since 1993, sandstorms have frequently occurred in Inner Mongolia, causing great economic losses. Some people think that sandstorm is caused by grassland degradation and desertification due to climate drought. It is a natural disaster, so it is inevitable.
Question: If true, which of the following would challenge the above statement, except?
A. A.In the 1950s, the grass on the Xilingol grassland in Inner Mongolia was as high as horses' bellies. Now the grass is too thick for mice.
B. B.Opposite the degraded grasslands of Hulunbuir and Xilingol in Inner Mongolia, the grasslands of Mongolia are about one meter tall.
C. C.Along the nearly uninhabited 10km-wide border between China and Mongolia, grass remains as tall as it was in the 1950s.
D. D.The increase in sandstorms is mainly caused by human factors such as overgrazing and predatory management of grasslands.
Answer: