With two in five plant species（物种）at risk of disappearance，the Germplasm Bank of Wild Species（中国西南野生生物种子资源库），or GBOWS，in Yunnan Province is racing against time to protect the nation's plant species.
Founded in 2007，GBOWS is a research and preservation（保存）bank for rare and endangered plants and animals. As the largest bank of wild species in Asia in terms of species，GBOWS has preserved 85，046 seeds from 10，601 species and 60，262 biological samples（生物样本）of 2，203 animal species. The number of seeds at GBOWS is close to that of the world's biggest seed bank—the Millennium Seed Bank in the United Kingdom.
So how does the bank work？Scientists collect the endangered and useful wild species and send them to the seed bank. Once the seeds arrive at GBOWS，they're dried and preserved in a special room. X-rays will make sure the seeds are undamaged and no insects are hidden inside after they are cleaned and separated from broken ones. The seeds are then frozen（冷藏），preserved in glass bottles and placed in a huge room at -20℃ for long-term preservation. Each bottle has a barcode（条形码）. By scanning it，scientists can view detailed information about the seeds inside.
The bank works with many international organizations on collection，exchange and research. It has 2，176 sets of seeds from 45 countries and regions，with each set including thousands of seeds.
"As China has rich and special plant and animal species，we plan to increase the number of our collections and conduct further research to protect endangered species，" says Li Pei，a worker at GBOWS. "If the world ends one day，these collections will bring hope of a new beginning to life on Earth. "
①The seeds are sent for X-rays.
②The dried seeds are put into a special room.
③The seeds are put into a room at -20℃.
④The broken seeds are taken out.
A. ②→④→①→③ B. ②→①→④→③ C. ④→②→①→③ D. ④→①→③→②
