Question

People who wish to become U.S. citizens must serve in the military for at least five years answer questions about U.S. history and government be permanently banished from their home country file an application with the U.S. Secret Service

Answer 1

the answer is

B. answer questions about U.S. history and government

Answer 2

People who wish to become U.S. citizens must "answer questions about U.S. history and government". Usually these questions are fairly basic and most people end up passing the test.