Forty-thousand of the world's young children die every day. This is 15 million a year. Many of these deaths can be prevented. In fact, experts say, techniques now exist to save the lives of half of these children. The techniques are medically effective, simple to use and low cost. The biggest task bas been to inform. parents about these life-saving techniques.
Diarrhea(腹泻)is the main cause of death among children in developing countries. Diarrhea results when the body tries to clear itself of harmful bacteria(细菌). The body does this by getting out liquids, sometimes uncontrollably. If too much water, sugar and salt are lost in this way, the body cannot work normally. The child may die.
The United Nations International Children's Fund, UNICEF, introduces a technique. It uses a simple mixture of sugar and salt in water. The mixture does not stop diarrhea. But if used often as needed, it keeps fluid (体液) levels normal until the body has fought off the harmful bacteria. In Egypt, for example, the treatment was used in a children's health care program in the province of Alexandria. It reduced by one-half the number of deaths caused by diarrhea. The technique bas now been used throughout the country.
According to the passage, a large number of children can be saved only when ________。

A. the life-saving ways are medically effective
B. their parents are rich enough for the life-saving techniques
C. the life-saving techniques are easy to use
D. their parents learn the life-saving techniques