“Drought is caused by weather patterns, but is worsened by human activities.” Choose two most likely reasons the author included the sentence in the passage.

• to explain the recent surge in China's attention to ecology
• to describe the cause of food shortages in areas of China
• to establish that industries are responsible for the condition of the Yellow River
• to establish that the condition of the Yellow River is connected to farming practices
• to substantiate the formation of the Loess Plateau Watershed Rehabilitation Project