Which course has more teachers, course no.16 or course no.18?
teachers refers to taughtBy.p_id; course no.16 refers to course_id = 16; course no.18 refers to course_id = 18
SELECT course_id FROM taughtBy WHERE course_id = 11 OR course_id = 18 GROUP BY course_id ORDER BY COUNT(course_id) DESC LIMIT 1