A.病例組的發(fā)病率與對(duì)照組的發(fā)病率之差B.病例組的發(fā)病率與對(duì)照組的發(fā)病率之比C.病例組的暴露比值與對(duì)照組的暴露比值的比D.病例組的暴露比值與對(duì)照組的暴露比值之差