Explanation:
the statement will create a role call REGISTRAR, grant UPDATE on student_grades to registrar, grant the role to user1,user2 and user3. Incorrect answer :
1: the statement does not contain error
2: there is no MODIFY privilege
4: statement does not create 3 users with the role
5: privilege is grant to role then grant to user
6: privilege is grant to role then grant to user

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