Read the given passage and answer the questions that follow.
A smile is more powerful than words. A sincere smile is a wonderful thing. A good salesperson knows that it's even more important than the value of the product. Incidentally, when a chimpanzee shows its teeth, the message is back off. Even crocodiles look as though they're smiling. According to Angus Trumble's book, "A Brief History of Smile," the nerves that make a natural smile are different from the nerves activated by a false one.
Consider the most famous smile of all, the Mona Lisa. In a 2003 study, Harvard professor Margaret Living Stone claimed that Leonardo Da Vinci painted the Mona Lisa so that if you stare straight at her mouth from a close range, the smile would be evident. Smile! A sincere smile is still a ray of light and hope in this world. Smiles tend to create their own weather systems. Fake it till you make it. Remember, when someone makes a disagreeable remark, a smile can help turn things around. So, smile!