Consider the following four relational schemas. For each schema, all non-trivial functional dependencies are listed

Schema I: Registration (rollno, courses)

Field ‘courses’ is a set-valued attribute containing the set of courses a student has registered for.

Non-trivial functional dependency:

rollno ® courses

Schema II: Registration (rollno, courseid, email)

Non-trivial functional dependencies:

rollno, courseid ® email email ® rollno

Schema III: Registration (rollno, courseid, marks, grade)

Non-trivial functional dependencies:

rollno, courseid ® marks, grade marks ® grade

Schema IV: Registration (rollno, courseid, credit)

Non-trivial functional dependencies:

rollno, courseid ® credit courseid ® credit

Which one of the relational schemas above is in 3NF but not in BCNF?

(A) Schema I              

(B) Schema II             

(C) Schema III           

(D) Schema IV

Ans: Schema II