有下列語句:
struct Birthday{public int year; public int month;
public int day;}; struct Student{ int no; string name;
int age; public Birthday bir; };
……
Student Stu;
如果要把Stu的出生年份賦值為1988,正確的語句是()
A. Stu.bir.year=1988;
B. Stu.year=1988;
C. Stu. Birthday.year=1988;
D. Student. Birthday.year=1988;