How to wash clothes in a flash LAUNDRY is never an easy part of housework. But if piles of sweaty   T-shirts and smelly socks drive you crazy, then two Chinese scientists might have the answer. Long Mingce and Wu Deyong of Shanghai Jiao Tong University have invented a kind of cotton that cleans itself. No need for soap or water, the scientists say. All you have to do is put the clothes out in the sun. According to the Guardian, this magical self-cleaning ability comes from a special chemical mixture. The material is covered with this mixture. It can break down dirt and remove bad smells after only a few hours in the sun.     One of the chemicals is called titanium dioxide  . Scientists have known for some time that titanium dioxide can clean fabrics  . However , it only works under ultraviolet   light and so is not yet widely used - ultraviolet light cannot be seen.    "We knew that self-cleaning cotton fabrics with titanium dioxide coating had already been developed, but they cannot work, or they work weakly, under sunlight," Long said. "If we want to use the fabrics in daily life, we must develop cotton that cleans itself under daylight."    The scientists worked hard for years to find a better chemical. Finally , they added silver iodide   into the mixture. This made the chemical reactions in sunlight faster. The new mixture is also nearly seven times better than the former one with pure titanium dioxide at removing dirt and killing bacteria.    The experiment was only carried out on cotton clothing. However, according to Long, the technology can be "applied to all kinds of fabrics and their related products." It is also cheap and environmentally friendly , he said.     The self-cleaning material is not yet ready for the market. Scientists still need to know whether it could harm people. Although titanium dioxide is used in some foods, it can cause health problems if it gets into the lungs  . Scientists need to make sure it is safe before we can start to enjoy the benefits of this technology . What might be a problem with the self-cleaning material ?
It will cause pollution. It costs too much to produce. It breaks down easily in the sun. It might cause health problems
Question: How to wash clothes in a flash LAUNDRY is never an easy part of housework. But if piles of sweaty   T-shirts and smelly socks drive you crazy, then two Chinese scientists might have the answer. Long Mingce and Wu Deyong of Shanghai Jiao Tong University have invented a kind of cotton that cleans itself. No need for soap or water, the scientists say. All you have to do is put the clothes out in the sun. According to the Guardian, this magical self-cleaning ability comes from a special chemical mixture. The material is covered with this mixture. It can break down dirt and remove bad smells after only a few hours in the sun.     One of the chemicals is called titanium dioxide  . Scientists have known for some time that titanium dioxide can clean fabrics  . However , it only works under ultraviolet   light and so is not yet widely used - ultraviolet light cannot be seen.    "We knew that self-cleaning cotton fabrics with titanium dioxide coating had already been developed, but they cannot work, or they work weakly, under sunlight," Long said. "If we want to use the fabrics in daily life, we must develop cotton that cleans itself under daylight."    The scientists worked hard for years to find a better chemical. Finally , they added silver iodide   into the mixture. This made the chemical reactions in sunlight faster. The new mixture is also nearly seven times better than the former one with pure titanium dioxide at removing dirt and killing bacteria.    The experiment was only carried out on cotton clothing. However, according to Long, the technology can be "applied to all kinds of fabrics and their related products." It is also cheap and environmentally friendly , he said.     The self-cleaning material is not yet ready for the market. Scientists still need to know whether it could harm people. Although titanium dioxide is used in some foods, it can cause health problems if it gets into the lungs  . Scientists need to make sure it is safe before we can start to enjoy the benefits of this technology . What might be a problem with the self-cleaning material ?
A. It will cause pollution.
B. It costs too much to produce.
C. It breaks down easily in the sun.
D. It might cause health problems
Answer: