列出各门课的平均成绩、最高成绩、最低成绩和选课人数。正确的 SQL 语句是 _____ 。
A.
SELECT 课号,AVG(成绩),MAX(成绩),MIN(成绩),COUNT() FROM 选课 GROUP BY 课号;
B.
SELECT 课号,AVG(成绩),MAX(成绩),MIN(成绩),COUNT() FROM 选课 ORDER BY 课号;
C.
SELECT 课号,AVG(成绩),MAX(成绩),MIN(成绩),COUNT() FROM 选课 WHERE 课号;
D.
SELECT 课号,AVG(成绩),MAX(成绩),MIN(成绩),COUNT() FROM 选课 HAVING 课号;