Task: Question Answering
Input (English): Before strip mining for coal, the topsoil in the area is removed and stored. After mining operations are completed, the land is leveled and topsoil is replaced. The purpose of replacing topsoil is  
 (A) to prevent wind from weathering and eroding surface coal. (B) to prevent radioactive elements from polluting water sources. (C) to provide an environment for new coal formation. (D) to restore the area to a natural condition.
Output (English): D