A、Mexico. B、Central America. C、U.S. D、Honduras. B新闻中提到墨西哥移民实际上正在逐渐离开美国，与此同时，中美洲的移民数量在上涨，故B为答案。原文是说墨西哥的移民实际上正在逐渐离开美国，并没有提到上涨，排除A和

In the last few years, the face of undocumented immigration to the U.S. has changed and so has the business of human smuggling. [3]Make no mistake, migrating illegally across the U.S.-Mexico border is a well established, booming business. Today on the show, we meet a businessman and a client in the evolving industry of human smuggling.
    For some context consider the changes in recent years: Mexican immigrants have actually been leaving America. Meanwhile, [4]Central American immigration is on the rise. This shift caused alarm when unaccompanied children from Honduras, El Salvador and Guatemala started showing up at the border seeking shelter. A new wave of people were making their way up through Mexico, trying to cross rivers and deserts to escape poverty and gang violence. And many of the people doing this were paying dearly for it.
3. What do we learn about the industry of human smuggling in the U.S.-Mexico border?
4. Whose immigration to America is on the rise?