题目

Food waste is a world's problem. Every year, about 1.3 billion tons, or one－third of all the food produced is thrown away, according to a survey. Using just 25 percent of that wasted food could feed 870 million hungry people, which would end world hunger. The people of France wasted 234 pounds of food per person, which is much better than some other countries. In the past, France wasn't good at controlling food waste, but now the country takes the lead.A law was made by French government. It made France the first country in the world to prevent supermarkets from throwing away unused food. No在△ABC中，已知||＝||＝||＝2，则向量·＝(　　)A．2B．－2C．2D．－2