单项选择题
设有以下定义和程序：
#include＜iostream.h＞
class A1
public:
void show 1()
cout＜＜" class A 1"＜＜end1;
class A2:public A1
public:
void show20
cout＜＜"class A2"＜＜end1;
;
class A3:protected A2
public:
void show3()
cout＜＜"class A 1 "＜＜end1;
;
void main()
A1 obj1;A2 obj2;A3 obj3;则以下不合语法的调用语句是(
)。A) obj1.show1();
B) obj2.show1();
C) obj3.show1();
D) obj2.show2();