3. Given a relational database schema with the following relation schema: Student (roll, name), Sem_subject_offer(subcode, subname), Sub_registration(roll, subcode, grade) Write the queries using SQL, relational algebra, tuple relational calculus, and domain relational calculus for each of the below: (a) Find the roll number and name of the students who have registered for all the subjects. (b) Find the name of the students who have secured Ex grade in all his/her registered subjects. (c) Find the name of the subjects for which maximum number of Ex grade were secured by the students. (d) Find the name of the subjects for which all its registered students secured only Ex grade. Also find the names of those students. (e) Find the name of those students who did not register for any of the subjects. [(0.5+0.5+0.5+0.5)5]