Question: Consider the following relation that stores information about offices, telephones and occupants of offices, Office (OfficeNum, Telephone Num, Occupant) Each office has a unique office number. There is only one telephone in each office and the telephone number is unique. Each office is occupied by only one person although a person may have more than one office. Occupant is a unique identification for persons occupying rooms. Which one of the following is correct?
1. OfficeNum and TelephoneNum are both candidate keys.
2. OfficeNum, TelephoneNum and (OfficeNum, TelephoneNum) are all candidate keys.
3. (OfficeNum, Occupant) and (TelephoneNum, Occupant) are the candidate keys.
4. OfficeNum must be the primary key.
Check Answer Correct Answer: OfficeNum and TelephoneNum are both candidate keys.