The correct answer is - lack of economic opportunities.
The seven countries in the Central American region are all if difficult economic conditions. The corruption is thriving, the economies are usually based on one or two products, and the industry and agriculture sectors are not well developed. The people that live in this countries are in general poor or on the verge of being poor, and the job opportunities in their respective countries are very limited and extremely hard to get.
Because of this reasons, the Central American people are migrating north, towards the United States, as they see it as a well developed country where they can find a better job, and have a better living in general.