Special ships that create clouds by sending seawater into the air could be the cheapest way of dealing with climate change, new research has found. The technique, known as "marine cloud whitening", would create clouds above the Pacific Ocean that would have a cooling effect by reflecting sunlight away from Earth. Nearly 2,000 wind-powered ships would cross the sea, getting seawater and sending it up through tall tubes. " When you send saltwater into the air, you create bigger and whiter clouds, and thus reflect more sunlight back into space," said David Young from the group of the study.  The paper by Professor Eric Bickel and Lee Lane looked into the costs of the projects. It found that cloud whitening would reduce the effects of climate change this century for no more than PS5.3 billion. This is only a small part of the PS150 billion that leading nations are considering spending to cut CO2 emissions   each year. It is also more than 25 times cheaper than the PS140 billion cost of another project which would copy the cooling effect of volcanoes.  The authors also compared the cost benefits that reducing temperatures would have. They found every PS1 spend on other ways would have PS15 of benefits, however every PS1 spent on cloud whitening would bring PS2,000 of benefits. These would include the human costs on health and the influence on other fields.  David Young said, "Marine cloud whitening could achieve as much for the planet as CO2cuts would, but with much less cost." But he warned that these techniques shouldn't be considered as a long-period way to deal with climate change. " It's important to note that this technique wouldn't reduce CO2emissions or deal with the causes of global warming, but would cover its effects." he said. Compared to other projects, cloud whitening   _  .
has a greater effect on volcanoes will bring more benefits will benefit man's health most can reduce temperatures in a better way
Question: Special ships that create clouds by sending seawater into the air could be the cheapest way of dealing with climate change, new research has found. The technique, known as "marine cloud whitening", would create clouds above the Pacific Ocean that would have a cooling effect by reflecting sunlight away from Earth. Nearly 2,000 wind-powered ships would cross the sea, getting seawater and sending it up through tall tubes. " When you send saltwater into the air, you create bigger and whiter clouds, and thus reflect more sunlight back into space," said David Young from the group of the study.  The paper by Professor Eric Bickel and Lee Lane looked into the costs of the projects. It found that cloud whitening would reduce the effects of climate change this century for no more than PS5.3 billion. This is only a small part of the PS150 billion that leading nations are considering spending to cut CO2 emissions   each year. It is also more than 25 times cheaper than the PS140 billion cost of another project which would copy the cooling effect of volcanoes.  The authors also compared the cost benefits that reducing temperatures would have. They found every PS1 spend on other ways would have PS15 of benefits, however every PS1 spent on cloud whitening would bring PS2,000 of benefits. These would include the human costs on health and the influence on other fields.  David Young said, "Marine cloud whitening could achieve as much for the planet as CO2cuts would, but with much less cost." But he warned that these techniques shouldn't be considered as a long-period way to deal with climate change. " It's important to note that this technique wouldn't reduce CO2emissions or deal with the causes of global warming, but would cover its effects." he said. Compared to other projects, cloud whitening   _  .
A. has a greater effect on volcanoes
B. will bring more benefits
C. will benefit man's health most
D. can reduce temperatures in a better way
Answer: