以下结构体类型说明和变量定义中正确的是

A)typedef struct

{int n; char c;} REC;

REC t1,t2;

B)struct REC;

{int n; char c;};

REC t1,t2;

C)typedef struct REC ;

{int n=0; char c='A';} t1,t2

D)struct

{int n;char c;}REC;

REC t1,t2;