주어진 문장이 들어갈 위치로 가장 적절한 곳은? However, bees are under threat, and the biggest offenders have been human beings. It is well known that bees are the main pollinators of the world. They help 90 percent of the world’s wildflowers to grow, and they also pollinate 35 percent of the world’s crops, including apples and tomatoes. ( ) Their involvement is vital to maintaining the biodiversity and health of ecosystems around the world. ( ) Our activities have destroyed the environment and food sources needed to sustain bee colonies. ( ) We have also inadvertently introduced dangerous predators and deadly pesticides. ( ) To counter these effects, United Nations officials are urging people to take action. They advise people to grow bee-friendly plants and stop using pesticides that can be harmful to bees.