Multiple choices:

48. In an existence-dependent relationship, the primary key of the dependent entity is a ________.

a. derived key

b. foreign key

c. composite key

d. surrogate key

49. When defining a 1:1 relationship where both sides of the relationship are mandatory, ________.

a. the foreign key that causes the fewest nulls should be selected

b. the model should be revised to ensure that the two entities do not belong together

c. the foreign key should be placed in the entity in which the relationship role in not played

d. the foreign key should be placed in both entities in the relationship

50. Which of the following is an example of time-variant data?

a. A person's Social Security number

b. A person's bank account balance

c. A manufactured part's serial number

d. An employee's date of birth