Q: Read the following article and answer the question. Article: Batteries are included, but the charger's not. The Nokia E-Cu concept phone doesn't need to plug in, it charges from any heat source. Designer Patrick Hyland says it can even work off the warmth of your pocket. The first time "it would take approximately seven hours to reach full charge, then after that it's continuously charging by keeping the phone in areas between 86 degrees and 104 degrees Fahrenheit." That's one hot pocket.? He's put a thermogenerator inside the phone that transforms heat into electric potential energy. To better conduct the heat to that little power plant in your pocket, the E-Cu (E for energy, Cu for copper) is coated by copper backing with heat sinks like those normally used to keep electronics from overheating. Nokia doesn't have current plans to build the phone, so for now it remains a concept. But Hyland says he's open to anyone who wants to cooperate. For Americans this technology would certainly be convenient. It would also save a bit on energy bills and waste. "Annually, unwanted phone chargers produce 51,000 tons of waste in addition to the greenhouse gases created by the production of the electricity needed to charge them," Hyland says. So a charger-free phone is also a green phone. Though adapting our plug in habits would help a group of people, most cell phone related energy use comes from leaving your charger plugged in all day unnecessarily. The real potential for charger-free cell phone technology is what it could enable places where plugging in isn't an option, like rural areas in the developing world. Cell phones are spreading faster than power lines and bringing with them countless opportunities, aid and health advances. A phone like the E-Cu, if it ever comes to be, would enable all manner of expanded aid and development by phone projects. Let's hope Patrick finds a partner. Question: A charger-free phone is friendly to the environment becasue . Answer:

Choose your answer from: 1). it is just a concept. 2). it is self-chargeable. 3). it brings convenience. 4). it is no waste of money.
A:
2).