How has increased illegal immigration affected the U.S. Border Patrol?

What is the BEST thesis statement for this initial research question?
A. Increases in illegal immigration in recent years have resulted in great strain on the U.S. Border Patrol.
B. Illegal immigration has increased. U.S. Border Patrol agents have decreased.
C. There is far more violence along the border than at any time in U.S. history. D. U.S. Border Patrol agents often find themselves conducting humanitarian missions.