Answer:
d. all of these are possible examples of data redundancy
Explanation:
Redundancy in database management systems (DBMS) is having the same data in more than one place.
If you look at the options, you will see all of them have situation that repeatation of the data.
a. storing the same information in several records
b. repeating data on multiple reports
c. using foreign keys which duplicate the values of primary keys
