Choose the number of the sentence that expresses the main idea in each selection. Then click "GO." 3. (1) The eruption of volcanoes has caused death and misery throughout the centuries. (2) But in parts of Italy, Iceland, Chile, and Bolivia, volcanic steam is used to run heat and power plants. (3) Pumice, which is made from volcanic lava, is used as a grinder and polisher. (4) Sulfur produced by volcanoes is useful to the chemical industry. (5) Hawaiian farmers grow crops on land made rich by decayed volcanic material. (6) Clearly, in spite of all the damage they cause, volcanoes do benefit us in various ways.