When Referring to Aircraft Identification,what Is the Significance of the "N

When referring to aircraft identification,what is the significance of the "N" number?

A) The "N" number is found on each side of the aircraft or on the vertical tail.
B) The "N" number designates a plane as being registered in the United States.
C) Most registered aircraft receive their "N" number when they are manufactured.
D) All of the preceding are significant in regard to the "N" number.