有如下存储过程:DELIMITER $$CREATE PROCEDURE p(IN POINT INT,OUT grade_level CHAR(3))BEGINCASEWHEN POINT>=90 THEN SELECT '优秀'INTO grade_level;WHEN POINT>=80 THEN SELECT '良好'INTO grade_level;WHEN POINT>=70 THEN SELECT '中等'INTO grade_level;WHEN POINT>=60 THEN SELECT '及格'INTO grade_level;ELSE SELECT '不及格'INTO grade_level;END CASE ;END $$DELIMITER ;下列调用该存储过程的语句中正确的是( )
A. CALL p(80, '良好');
B. CALL p(85, @s);
C. RETURN p(80, '良好');
D. RETURN p(85, @s);