This is everything that is given, i.e. there is only one relation

Returning to the Enroll(sid, dept, cnum, sec) example which shows the enrollment f or this quarter: (a) Write an SQL query to find the students who are only enrolled in the CS classes offered this quarter. (b) Write and SQL query to find the students who are enrolled in all the CS classes offered this quarter. (c) Write the previous queries using different SQL constructs. In particular can you express those queries using the count aggregate? Please explain