单选题 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();