单选题：以下对类A的定义,哪个是正确的?

以下对类A的定义,哪个是正确的? @[B](2)

A. `class A{
private:int v;
public:void fun(){}
}`
B. `class A{
int v;
A * next;
void fun(){}
};`
C. `class A{
int v;
public:
void fun();
};
A::void fun(){}`
D. `class A{
int v;
public:
A next;
void fun(){}
};`




A.`class A{
private:int v;
public:void fun(){}
}`
B.`class A{
int v;
A * next;
void fun(){}
};`
C.`class A{
int v;
public:
void fun();
};
A::void fun(){}`
D.`class A{
int v;
public:
A next;
void fun(){}
};`


答案：B