One of the world's richest men has taken a close interest in one of man's most basic functions: visiting the toilet.Bill Gates's charitable organization, the Bill and Melinda Gates Foundation, is looking for inventors to design the loo of the future, which, they hope, would improve sanitation for millions of people around the world. So, what's wrong with the traditional flush toilet? Firstly, it wastes a huge amount, of potential drinking water.Secondly, they are more likely to cause pollution.This is a real problem in many areas of the developing world, where, according to United Nations estimates, unsafe sanitation causes half of all hospitalizations.Younger people are particularly at risk.Illnesses which cause diarrhea are responsible for the deaths of about 1.5 million children a year.Finally, standard lavatories simply aren't practical in remote areas. The challenge set by Bill Gates was to come up with a _ which works without running water, electricity or aseptic tank.It also needed to operate for less than 5 cents.28 designs were displayed at the recent Reinvent the Toilet Fair.in Seattle, USA.Among them was one which turned human waste into electricity using microwaves, another which converted human waste into charcoal, and yet another which used urine for flushing. But the winner was a solar-powered design which generated hydrogen gas and electricity.The team from the California Institute of Technology(CIT)picked up a prize of $ 100,000. But clearly Bill Gates doesn't feel he's _ .After the Seattle event he said, "We, couldn't be happier with the response we've gotten," Gates has even pledged $370 million more to the future toilet project.They hope to field test more, prototypes over the next three years. If someone "flush money down the toilet", they are  _  .
wasting money for nothing being angry with their work conditions showing--off their wealth expressing their great determination
Question: One of the world's richest men has taken a close interest in one of man's most basic functions: visiting the toilet.Bill Gates's charitable organization, the Bill and Melinda Gates Foundation, is looking for inventors to design the loo of the future, which, they hope, would improve sanitation for millions of people around the world. So, what's wrong with the traditional flush toilet? Firstly, it wastes a huge amount, of potential drinking water.Secondly, they are more likely to cause pollution.This is a real problem in many areas of the developing world, where, according to United Nations estimates, unsafe sanitation causes half of all hospitalizations.Younger people are particularly at risk.Illnesses which cause diarrhea are responsible for the deaths of about 1.5 million children a year.Finally, standard lavatories simply aren't practical in remote areas. The challenge set by Bill Gates was to come up with a _ which works without running water, electricity or aseptic tank.It also needed to operate for less than 5 cents.28 designs were displayed at the recent Reinvent the Toilet Fair.in Seattle, USA.Among them was one which turned human waste into electricity using microwaves, another which converted human waste into charcoal, and yet another which used urine for flushing. But the winner was a solar-powered design which generated hydrogen gas and electricity.The team from the California Institute of Technology(CIT)picked up a prize of $ 100,000. But clearly Bill Gates doesn't feel he's _ .After the Seattle event he said, "We, couldn't be happier with the response we've gotten," Gates has even pledged $370 million more to the future toilet project.They hope to field test more, prototypes over the next three years. If someone "flush money down the toilet", they are  _  .
A. wasting money for nothing
B. being angry with their work conditions
C. showing--off their wealth
D. expressing their great determination
Answer: