Many cities around the world today are heavily polluted. Careless methods of production and lack of consumer demand   for environment friendly products have contributed to the pollution problem. One result is that millions of tons of glass, paper, plastic and metal container are produced, and these are difficult to get rid of. However, today, more and more consumers are choosing "green" and demanding that the products they buy should be safe for the environment. Before they buy a product, they ask questions like these, "Will this shampoo damage the environment?" "Can this metal container be reused or can it only be used once?" A recent study showed that two out of five adults now consider the environment safety of a product before they buy it. This means that companies must now change the way they make and sell their products to make sure that they are "green", that is, friendly to the environment. Only a few years ago, it was impossible to find green products in supermarkets, but now there are hundreds. Some supermarkets' products carry labels   to show that the product is green. Some companies have made producing of clean and safe products their main selling points and emphasize   it in their advertising. The concern for a safer and cleaner environment is making companies rethink how they do business. No longer will the public accept the old attitude of "Buy it, use it, throw it away, and forget it." The public pressure is on, and gradually business is cleaning up its act. It becomes clear from the passage that the driving force   behind the green products is   _  .
public caring for the environment companies' desire for bigger sales new ways of doing business rapid growth of supermarkets