When people who come to the U. S. from foreign countries want to become citizens, they must go through a process called naturalization. The process requires them to file an application, take a naturalization test, and appear in court.

In the passage above, what does the word naturalization mean?
A.
a test that people must take to become U.S. citizens
B.
an application for citizenship in the U.S.
C.
the process by which people may become U.S. citizens
D.
a test that foreigners must take before entering the U.S.