听力原文：United Nations records show people the world over are getting older. This is due

听力原文： United Nations records show people the world over are getting older. This is due to better medicine and more food, even in developing countries. Another global statistic: there are fewer younger people able to provide health care and other services for the elderly. Other U.N. statistics show that by the year 2050, people 60 years or older will account for half of the increase in the world's population. The United States is already experiencing nursing shortages and expects other staffing shortages in health Care in the coming years. U.S. Secretary of State Condoleezza Rice described this trend as one of the greatest challenges that most nations will face this century. "Nations around the world are taking notice of the challenges of aging, but too many are still wrestling with them independent of one another, when we all stand to benefit from sharing our common solutions to these common problems:" Secretary Rice said one of the key goals of the summit was to open international discussions on this trend and to encourage research to provide the answers to the challenges posed by global aging.

According to United Nations records, people all over the world are getting older because of______.

A．good health care and other services

B．fewer and fewer challenges and pressures

C．more international discussions between countries

D．better medicine and more food