Which of the following is true regarding subclasses?
A) a subclass that inherits methods from its superclass may not override the methods
B) a subclass that inherits instance variables from its superclass can not declare additional instance variables
C) a subclass may inherit methods or instance variables from its superclass but not both
D) a subclass may inherit methods from instance variables from its superclass, and may also implement its own methods and declare its own instance variables