[Taivalsaari1996] According to the author. Formally, inheritance can be characterized as follows [Bracha and Cook 1990; Cook 1989a; Wegner and Zdonik 1988]:

R = P XOR DELTA R

As a result of this maxim, . Which one of the following statements is NOT correct?
A. P is known as R's parent or immediate ancestor.
B. In class-based systems, P is superclass of R.
C. R is P's child, or immediate descendant.
D. In class-based systems R is subclass of P.