题目

On Saturday, millions of people around the world will celebrate Saint Patrick's Day, which honors Patron Saint (or main religious figure) of Ireland. Communities across the United States will host parades, parties, and other festivities to mark the occasion. This year, cities like Boston, New York, and Chicago have organized massive events celebrating Saint Patrick's Day. In New York City, hundreds of thousands of people will gather to watch the Saint Patrick’s Day parade—the nation’s largest. It is one of the most watched parades in the world. Last year, almost 2 million spectators and 一家电信公司提供两种手机的月通话收费方式供用户选择，其中一种有月租费，另一种无月租费．这两种收费方式的通话费用y（元）与通话时间x（分钟）之间的函数关系如图所示．小红根据图象得出下列结论：①l1描述的是无月租费的收费方式；②l2描述的是有月租费的收费方式；③当每月的通话时间为500分钟时，选择有月租费的收费方式省钱．其中，正确结论的个数是（　　）.A.0B.1C.2D.3