?The three normal forms constitute a progression in which the second normal form represents the best design.

Which statement is true when a base class has protected instance variables?

a) A derived class object can assign an invalid value to the base class’s instance variables, thus leaving the object in an inconsistent state. b) Derived class methods are more likely to be written so that they depend on the base class’s data implementation. c) We may need to modify all the derived classes of the base class if the base class implementation changes. d) All of the above.

The ____________________ is the vertical line to the left of the graph.

Fill in the blank(s) with the appropriate word(s).