Final answer:
C++ improves upon the C struct datatype by allowing member functions, supporting inheritance, and introducing encapsulation, thus enabling the struct to have features of object-oriented programming.
Step-by-step explanation:
C++ improves upon the C struct datatype by incorporating features that support object-oriented programming. Unlike in C where struct only contains fields or properties, C++ enhances struct in three main ways:
- By allowing member functions, C++ structs can have functions defined inside them which allows them to operate on their data, similarly to methods in a class.
- By supporting inheritance, C++ allows structs to inherit properties and behaviors from other structs or classes, enabling the creation of a hierarchy of types.
- By introducing encapsulation, C++ structs (and classes) can enforce access restrictions to their members, thereby allowing for both public and private data members.
The correct answer to the given question is D) All of the above, as these features collectively mark the improvements that C++ has made to the C struct datatype.