GATE Computer Science (CS) 2018 Shift 1 Solved Paper

Consider the following four relational schemas. For each schema, all non-trivial functional dependencies are listed. The underlined attributes are the respective primary keys.
Schema I : Registration (rollno, courses)
Field ‘courses’ is a set-valued attribute containing the set of courses a studenthas registered for.
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?