(1) Finding a good way to get rid of garbage is a problem that faces many municipalities today. (2) It may be of some consolation for them to know that getting rid of garbage has almost always involved problems. (3) When settlements were very small, garbage was simply thrown outdoors, where it eventually decomposed. (4) But as communities grew, pigs and other animals helped clear away garbage by eating it; of course, the animals, in turn, recycled that garbage and thus created an even less appealing garbage problem. (5) The first municipal effort to deal with garbage was begun in Philadelphia by Benjamin Franklin, whose solution was to have it dumped into the Delaware River. (6) A century later, municipal incinerators, generally located in the most crowded part of town, burned garbage and produced the worst of odors as a by-product. The sentence that expresses the main idea is: (Choose the number of the sentence. Then click the arrow.)