Which of the following assignments would be a compilation error? Assigning the address of a derived-class object to a base-class pointer. Assigning the address of a base-class object to a base-class pointer. Assigning the address of a derived-class object to a derived-class pointer. Assigning the address of a base-class object to a derived-class pointer.

The last assignment, assigning the address of a base-class object to a derived-class pointer, would lead to a compilation error. This is because a base-class object doesn’t possess the additional properties or behaviors defined in the derived class; thus, there's no safe way to interpret the base-class object as the derived class. In C++, pointers and references primarily follow the "is-a" relationship, which means that a derived-class object can be treated as a base-class object. However, the reverse isn’t true. If you attempt to assign a base-class object to a derived-class pointer, it violates this object-oriented principle and leads to ambiguity about the object type, resulting in a compilation error.