studying population growth短文的第一句提到人口的上升直接影响到环境，由此确认文章的中心是人口与环境的关系问题。此题问的是联合国人口基金组织的任务，文中用了beresponsible for，考生理解这个短语的意思才能正确答题。

A new report says the growing population around the world is harming the environment. More people are using more of the Earth’s natural resources than ever before. Experts say poor people around the world will suffer most in the future unless environmental damage is stopped. They say more should be done to balance human and environmental needs.
    The United Nations Population Fund is responsible for studying population growth. It released the report about the subject. It examines the links among environmental conditions, population growth and efforts to help poor people in developing countries.
    The world population is now more than 6,000 million people. That number has increased by 100% since 1960. The population is expected to increase to more than 9,000 million by the year 2050. The report says about 2,000 million people lack food security. Water supplies and agricultural lands are heavily used. In 50 years, experts say more than 4,000 million people will be living in countries that can not meet people’s daily needs.
    The report says all of the expected growth in world population will take place in developing countries. The 49 least developed countries are expected to increase by almost 200% in 50 years.
    Yet, the U-N agency says people in the richest countries use much more of the world’s resources than people in developing countries. It says a child born today in the United States, France or Japan will do more harm to the environment during his lifetime than as many as 50 children born in developing countries.
    The U-N Population Fund says international policies need to be put into effect to improve poor conditions, increase social development and ease pressure on the environment. It also says women need more control over their lives. It says empowering women would lead to smaller families and slower population growth. The U-N Population Fund says these measures would help improve the well being of growing populations while protecting the natural world.