Your smartphone can do a lot of things. It can call people. It connects to the Internet. It enables you to play fun games. But there is a _ side to this smart little equipment of yours----- it might also spread disease. "People are just likely to get sick from their phones as from handles of the bathroom, " Jeffrey Cain, the president of the American Academy of Family Physicians , told The Wall Street Journal. This may be hard to believe, but scientists reached this conclusion after they tested eight cell phones from an office in Chicago. All the tested phones showed high numbers of coliforms  , a kind of bacteria found in human waste , with about 2700 to 4200 units of the bacteria on each phone. The bacteria can cause flu, pinkeye and other diseases . That is right --- your phone is covered in our human waste. Although computers, keys and pens carry germs   , our phones get far dirtier. They touch a lot of things, including our hands and the inside of our pocket or purse. We take them almost everywhere: the bus, the subway and who hasn't played Angry Birds or Fruit Ninja while sitting on the toilet? "Some things that we think are personal are actually more public than we imagine," Cain said.  What is even worse is that after the phone returns from its dirty trip, it then spends most of its time cozying up to our faces. You don't think about how often you touch your phone to your face, do you? Our noses, mouths and ears are all warm and rich in grease   , an environment that germs really like. So how do you keep your phone clean? Alcohol is effective when used to kill germs from the back and side of your phone. But it might harm the screen. There is one simple and reliable way you can reduce the germs on your phone's surface: wash your hands regularly. What is the article mainly about?
Tips on the use of phones Health problems caused by the use of phones The danger of coliforms infection The influence that phone have on our life
Question: Your smartphone can do a lot of things. It can call people. It connects to the Internet. It enables you to play fun games. But there is a _ side to this smart little equipment of yours----- it might also spread disease. "People are just likely to get sick from their phones as from handles of the bathroom, " Jeffrey Cain, the president of the American Academy of Family Physicians , told The Wall Street Journal. This may be hard to believe, but scientists reached this conclusion after they tested eight cell phones from an office in Chicago. All the tested phones showed high numbers of coliforms  , a kind of bacteria found in human waste , with about 2700 to 4200 units of the bacteria on each phone. The bacteria can cause flu, pinkeye and other diseases . That is right --- your phone is covered in our human waste. Although computers, keys and pens carry germs   , our phones get far dirtier. They touch a lot of things, including our hands and the inside of our pocket or purse. We take them almost everywhere: the bus, the subway and who hasn't played Angry Birds or Fruit Ninja while sitting on the toilet? "Some things that we think are personal are actually more public than we imagine," Cain said.  What is even worse is that after the phone returns from its dirty trip, it then spends most of its time cozying up to our faces. You don't think about how often you touch your phone to your face, do you? Our noses, mouths and ears are all warm and rich in grease   , an environment that germs really like. So how do you keep your phone clean? Alcohol is effective when used to kill germs from the back and side of your phone. But it might harm the screen. There is one simple and reliable way you can reduce the germs on your phone's surface: wash your hands regularly. What is the article mainly about?
A. Tips on the use of phones
B. Health problems caused by the use of phones
C. The danger of coliforms infection
D. The influence that phone have on our life
Answer: