有以下程序：
ClAssDAtE
puBliC:
DAtE(int y,int m,int D);
yEAr = y;
month = m;
DAy = D;
DAtE(int y = 2000)
yEAr = y;
month = 10;
DAy = 1;
DAtEDAtE &D)
yEAr =D、yEAr;
month =D、month;
DAy =D、DAy;
voiD print()
Cout＜＜yEAr＜＜"."＜＜month＜＜"."＜＜DAy＜＜EnDl;
privAtE:
int yEAr,month,DAy;
;
DAtE FunDAtE D)
DAtE tEmp;
tEmp = D;
rEsurn tEmp;
int mAin ()
DAtE DAtE1 (2000,1,1),DAtE2 (0,0,0);
DAtE DAtE3 (DAtE1);
DAtE2 = Fun(DAtE3);
rEturn 0;
程序执行时，DAtE类的拷贝构造函数被调用的次数是
A．2
B．3
C．4
D．5