Question: or a C? | You want the students just with grade "C" or including "A" | Who got either an A or a C?
SQL: SELECT count ( T1.stu_fname )  FROM student AS T1 JOIN enroll AS T2 ON T1.stu_num   =   T2.stu_num WHERE T2.enroll_grade   =   'C' OR T2.enroll_grade   =   'A'