Question: Among the easiest courses, what is the name of the course where most students got an A?
SQL: SELECT T2.name FROM registration AS T1 INNER JOIN course AS T2 ON T1.course_id = T2.course_id WHERE T1.grade = 'A' AND T2.diff = 1 GROUP BY T2.name ORDER BY COUNT(T1.student_id) DESC LIMIT 1