This is _____ chalk. _____ chalk is on the desk.[ ]

A. \ , The                                                      

B. a, the                     

C. an, The                                      

D. a, A

某数据库中有表COURSE(CNO，CNAME，TNO)和表TEACHER(TNO，TNAME，DEPART)，完成查询选修某课程的同学人数多于5人的教师姓名。
SELECT TNAME
FROM TEACHER WHERE
______
(SELECT X.TNO FROM COURSE X，COURSE Y
WHERE ______
______
______)