The university registrar database has the following schema: student: sid (string) course: cid (string) prerequisite: cid (string), pre_cid (string) record: sid (string), cid (string), quarter (string), year (integer), grade (integer) Relation student provides the ids of all students enrolled in the university, and course provides all courses offered (identified by strings using letters and numbers). Relation prerequisite provides the prerequisites pre_cid for each course cid. Relation record indicates which courses were taken by each student in a given year and quarter (F, W, S), and the grade obtained (for simplicity, grades are provided as integers 4, 3, 2, 1,0, corresponding to A, B, C, D, F). Assume that a class can only be taken once. Note that students may have gaps in enrollment, i.e. they need not take courses every quarter. Also, there may be students who have not yet taken any course, and courses that have not yet been taken by any student. In addition, the following hold: sid is the primary key of student cid is the primary key of course {cid, pre_cid} is the primary key of prerequisite; cid and pre_cid are foreign keys referencing course. {sid, cid} is the primary key of record (so each student can only take a course once) grades are unique for each course taken by a student in a given year and quarter), sid is a foreign key referencing student and cid is a foreign key referencing course. For each course occurring in record, find the quarter(s) with its highest enrollment. The answer should have attributes {cid, quarter, year, enrollment} The university registrar database has the following schema: student: sid (string) course: cid (string) prerequisite: cid (string), pre_cid (string) record: sid (string), cid (string), quarter (string), year (integer), grade (integer) Relation student provides the ids of all students enrolled in the university, and course provides all courses offered (identified by strings using letters and numbers). Relation prerequisite provides the prerequisites pre_cid for each course cid. Relation record indicates which courses were taken by each student in a given year and quarter (F, W, S), and the grade obtained (for simplicity, grades are provided as integers 4, 3, 2, 1,0, corresponding to A, B, C, D, F). Assume that a class can only be taken once. Note that students may have gaps in enrollment, i.e. they need not take courses every quarter. Also, there may be students who have not yet taken any course, and courses that have not yet been taken by any student. In addition, the following hold: sid is the primary key of student cid is the primary key of course {cid, pre_cid} is the primary key of prerequisite; cid and pre_cid are foreign keys referencing course. {sid, cid} is the primary key of record (so each student can only take a course once) grades are unique for each course taken by a student in a given year and quarter), sid is a foreign key referencing student and cid is a foreign key referencing course. For each course occurring in record, find the quarter(s) with its highest enrollment. The answer should have attributes {cid, quarter, year, enrollment}