Questions 29 and 30 are based on the following news. At the end of the news item , you will be given 10 seconds to answer the questions.
Now listen to the news.
Officials believe that ______ are responsible for the destruction of nearly 20,000 square kilometers of jungle.

A．By
B．At
C．In
D．On

A．the rate of deforestation of the Amazon rainforest has increased about 15 percent over last year
B．the rate of air pollution has increased about 15 percent over last year
C．the rate of land decreasing has increased about 15 percent over last year
D．the amount of rainfall has increased about 15 percent over last year